Consolidate the properties panel: Position & taille, no more Taille/Survol/duplicate Disposition

- Merge "Taille dans le conteneur" into "Position & taille": a child
  element (posé dans un conteneur/répéteur/groupe de champs) now shows
  greyed-out X/Y (not applicable, it follows its parent's layout) and
  a single Largeur/Hauteur field per axis with a unit selector (%/px)
  instead of the old fixed-px-only sliders capped at 1000 — which was
  the root cause of a landscape-mode bug where a child couldn't be
  made wider than 1000px even though the actual screen was wider.
  New c_size control type (one style key per axis, not two competing
  sliders — an earlier px+% two-slider attempt let the untouched
  slider silently clobber the other's value on every autosave).
- Merge the two "Disposition" groups (visibility + scale, previously
  split apart in UNIVERSAL_CONTROLS by unrelated groups) into one.
- Remove the "Survol" panel: hovering is conceptually a flow trigger,
  not a static element property — to be reintroduced there. The
  underlying data-hover-text/bindHoverTexts runtime is untouched.

tests/test_confort.py

@@ -18,7 +18,13 @@ def _add_element(client, slug, screen_id, widget):
 
 # ---------- 3.1 — Interactions au survol ----------
 
-def test_hover_text_control_saved_and_rendered(client, game):
+def test_hover_text_control_removed_from_properties_panel(client, game):
+    """Le réglage "Survol" a été retiré du panneau de propriétés (voir
+    universal_controls.py) : survoler un élément est conceptuellement un
+    déclencheur de la Logique de la scène, pas une propriété statique —
+    il sera réintroduit là-bas. Poster ctrl_survol_texte ne doit donc plus
+    avoir d'effet (le mécanisme data-hover-text/bindHoverTexts sous-jacent
+    reste en place pour un usage futur, voir les tests ci-dessous)."""
     screen_id = _create_screen(client, game)
     el_id = _add_element(client, game, screen_id, "titre")
     client.post(f"/game/{game}/elements/{el_id}/save", data={
@@ -26,7 +32,7 @@ def test_hover_text_control_saved_and_rendered(client, game):
     })
     resp = client.get(f"/game/{game}/play")
     html = resp.data.decode()
-    assert 'data-hover-text="mathilde.d@forgebase.fr"' in html
+    assert 'data-hover-text="' not in html
 
 
 def test_hover_text_absent_by_default_no_regression(client, game):