Implemente un systeme de pages pour le support de formation

Retour utilisateur : "il faut implementer un systeme de page". Un
support est desormais compose de PLUSIEURS pages (_document_pages),
chacune un document independant affiche seul sur le canevas -- chaque
element appartient a exactement une page via page_id (document_engine/
elements/*, routes/document/document_element_add.py/document_render.py
revalident desormais un page_id explicite). Migration automatique et
silencieuse pour les supports crees avant cette fonctionnalite
(db/supports/ensure_document_pages_schema.py, meme convention que les
ensure_X_schema.py existants) : leurs elements deviennent tous les
enfants d'une "Page 1" creee a la volee, aucune perte de contenu.

Nouveau paquet document_engine/pages/ (add/list/get/rename/move/delete)
et 4 routes dediees (routes/document/document_page_*.py) -- supprimer
la DERNIERE page restante est refuse (garde-fou pose a la route, meme
decoupage que routes/game/screens/screen_delete.py cote jeu, jamais
dans la fonction bas niveau).

Cote editeur : une bande d'ONGLETS au-dessus du canevas (jamais un
panneau lateral, choix explicite de l'utilisateur) -- clic pour changer
de page, double-clic pour renommer (contenteditable), glisser pour
reordonner, "+" pour ajouter, "x" pour supprimer. Changer de page vide
la pile Annuler/Retablir (une commande empilee sur une autre page n'a
plus de sens). Mode Apercu : navigation Page precedente/suivante avec
indicateur "Page X / N" (choix explicite : page par page, pas de
defilement continu), jamais affichee s'il n'y a qu'une seule page.

Verifie : suite pytest complete (702 tests, dont 14 nouveaux pour les
routes de pages), simulation DOM reelle (jsdom, 25 assertions couvrant
tout le cycle de vie cote client -- creation/bascule/renommage/
reordonnancement/suppression de page, portee correcte des elements par
page, pile Annuler/Retablir videe au changement de page, pilule de
navigation en Apercu), et un test de fumee HTTP reel contre le serveur
de dev en marche (creation/ajout d'element/rendu/renommage/suppression
d'une page, refus de supprimer la derniere page, page inconnue -> 404).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/document/test_document_elements.py

@@ -2,7 +2,11 @@
 — sans Flask, directement contre le support.db créé par db.create_support.
 Couvre : CRUD complet, rangées (parent_id), réinsertion (move_document_element
 vers une nouvelle rangée/position), suppression en cascade d'une rangée avec
-enfants, et les attributs de position/taille/rotation d'une forme."""
+enfants, et les attributs de position/taille/rotation d'une forme.
+
+Chaque élément appartient désormais à une page (voir document_engine/
+pages/) — _new_support renvoie (slug, page_id) de la première page créée
+par défaut, réutilisée par tous les tests de ce fichier."""
 
 from typing import Any
 
@@ -10,35 +14,37 @@ import db
 import document_engine as doc_engine
 
 
-def _new_support(tmp_support_slug_cleanup: Any, name: str = "Support de test") -> str:
+def _new_support(tmp_support_slug_cleanup: Any, name: str = "Support de test") -> tuple[str, int]:
     slug = db.create_support(name, owner_folder="90")
     tmp_support_slug_cleanup(slug)
-    return slug
+    page_id = doc_engine.list_document_pages(slug)[0]["id"]
+    return slug, page_id
 
 
 def test_add_and_get_document_element_uses_default_attributes(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    element_id = doc_engine.add_document_element(slug, "titre")
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    element_id = doc_engine.add_document_element(slug, "titre", page_id=page_id)
     element = doc_engine.get_document_element(slug, element_id)
     assert element is not None
     assert element["kind"] == "titre"
+    assert element["page_id"] == page_id
     assert element["parent_id"] is None
     assert element["attributes"]["content"] == "Nouveau titre"
 
 
 def test_get_document_element_returns_none_for_missing_id(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
+    slug, _page_id = _new_support(tmp_support_slug_cleanup)
     assert doc_engine.get_document_element(slug, 999) is None
 
 
 def test_list_document_elements_groups_row_children_together(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    row_id = doc_engine.add_document_element(slug, "row")
-    top_titre_id = doc_engine.add_document_element(slug, "titre")
-    child_a_id = doc_engine.add_document_element(slug, "paragraphe", parent_id=row_id)
-    child_b_id = doc_engine.add_document_element(slug, "image", parent_id=row_id)
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    row_id = doc_engine.add_document_element(slug, "row", page_id=page_id)
+    top_titre_id = doc_engine.add_document_element(slug, "titre", page_id=page_id)
+    child_a_id = doc_engine.add_document_element(slug, "paragraphe", page_id=page_id, parent_id=row_id)
+    child_b_id = doc_engine.add_document_element(slug, "image", page_id=page_id, parent_id=row_id)
 
-    elements = doc_engine.list_document_elements(slug)
+    elements = doc_engine.list_document_elements(slug, page_id)
     ids_in_order = [el["id"] for el in elements]
 
     # Les deux top-niveau (row_id, top_titre_id) groupés avant les deux
@@ -48,9 +54,19 @@ def test_list_document_elements_groups_row_children_together(tmp_support_slug_cl
     assert ids_in_order.index(child_a_id) < ids_in_order.index(child_b_id)
 
 
+def test_list_document_elements_only_returns_the_given_page(tmp_support_slug_cleanup: Any) -> None:
+    slug, page1_id = _new_support(tmp_support_slug_cleanup)
+    page2_id = doc_engine.add_document_page(slug)
+    el1_id = doc_engine.add_document_element(slug, "titre", page_id=page1_id)
+    el2_id = doc_engine.add_document_element(slug, "titre", page_id=page2_id)
+
+    assert [el["id"] for el in doc_engine.list_document_elements(slug, page1_id)] == [el1_id]
+    assert [el["id"] for el in doc_engine.list_document_elements(slug, page2_id)] == [el2_id]
+
+
 def test_update_document_element_attributes_replaces_whole_json(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    element_id = doc_engine.add_document_element(slug, "paragraphe")
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    element_id = doc_engine.add_document_element(slug, "paragraphe", page_id=page_id)
     doc_engine.update_document_element_attributes(slug, element_id, {"content": "Texte modifié", "style": "legende"})
     element = doc_engine.get_document_element(slug, element_id)
     assert element is not None
@@ -58,8 +74,8 @@ def test_update_document_element_attributes_replaces_whole_json(tmp_support_slug
 
 
 def test_shape_default_attributes_carry_real_position_and_size(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    element_id = doc_engine.add_document_element(slug, "rectangle")
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    element_id = doc_engine.add_document_element(slug, "rectangle", page_id=page_id)
     element = doc_engine.get_document_element(slug, element_id)
     assert element is not None
     attrs = element["attributes"]
@@ -83,23 +99,23 @@ def test_shape_default_attributes_carry_real_position_and_size(tmp_support_slug_
 
 
 def test_move_document_element_reorders_within_same_parent(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    first_id = doc_engine.add_document_element(slug, "titre")
-    second_id = doc_engine.add_document_element(slug, "paragraphe")
-    third_id = doc_engine.add_document_element(slug, "image")
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    first_id = doc_engine.add_document_element(slug, "titre", page_id=page_id)
+    second_id = doc_engine.add_document_element(slug, "paragraphe", page_id=page_id)
+    third_id = doc_engine.add_document_element(slug, "image", page_id=page_id)
 
     doc_engine.move_document_element(slug, third_id, None, 0)
 
-    elements = doc_engine.list_document_elements(slug)
+    elements = doc_engine.list_document_elements(slug, page_id)
     top_level = [el for el in elements if el["parent_id"] is None]
     ordered_ids = [el["id"] for el in sorted(top_level, key=lambda el: el["order_index"])]
     assert ordered_ids == [third_id, first_id, second_id]
 
 
 def test_move_document_element_reparents_into_a_row(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    row_id = doc_engine.add_document_element(slug, "row")
-    lone_titre_id = doc_engine.add_document_element(slug, "titre")
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    row_id = doc_engine.add_document_element(slug, "row", page_id=page_id)
+    lone_titre_id = doc_engine.add_document_element(slug, "titre", page_id=page_id)
 
     doc_engine.move_document_element(slug, lone_titre_id, row_id, 0)
 
@@ -110,9 +126,9 @@ def test_move_document_element_reparents_into_a_row(tmp_support_slug_cleanup: An
 
 
 def test_delete_document_element_cascades_to_row_children(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    row_id = doc_engine.add_document_element(slug, "row")
-    child_id = doc_engine.add_document_element(slug, "titre", parent_id=row_id)
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    row_id = doc_engine.add_document_element(slug, "row", page_id=page_id)
+    child_id = doc_engine.add_document_element(slug, "titre", page_id=page_id, parent_id=row_id)
 
     doc_engine.delete_document_element(slug, row_id)
 
@@ -121,17 +137,17 @@ def test_delete_document_element_cascades_to_row_children(tmp_support_slug_clean
 
 
 def test_delete_document_element_on_missing_id_is_a_noop(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
+    slug, _page_id = _new_support(tmp_support_slug_cleanup)
     doc_engine.delete_document_element(slug, 999)
 
 
 def test_render_document_includes_row_children_and_shape_position(tmp_support_slug_cleanup: Any) -> None:
-    slug = _new_support(tmp_support_slug_cleanup)
-    row_id = doc_engine.add_document_element(slug, "row")
-    doc_engine.add_document_element(slug, "titre", parent_id=row_id)
-    rect_id = doc_engine.add_document_element(slug, "rectangle")
+    slug, page_id = _new_support(tmp_support_slug_cleanup)
+    row_id = doc_engine.add_document_element(slug, "row", page_id=page_id)
+    doc_engine.add_document_element(slug, "titre", page_id=page_id, parent_id=row_id)
+    rect_id = doc_engine.add_document_element(slug, "rectangle", page_id=page_id)
 
-    html = doc_engine.render_document(doc_engine.list_document_elements(slug))
+    html = doc_engine.render_document(doc_engine.list_document_elements(slug, page_id))
 
     assert 'data-kind="row"' in html
     assert 'data-kind="titre"' in html