Turn free-typed field/object names into dropdowns in the Répéteur and Donnée liée filters

Two settings previously required typing an exact field or object name by hand:

- "champ" (Répéteur's filtre_champ/filtre2_champ, Donnée liée's data_filtre_champ/data_filtre2_champ) is now a dropdown of the actual fields on the object already chosen for that widget — pre-populated server-side (controls_with_values.py) and live-updated client-side without a reload when you change the object (bindDefinitionFieldSelects(), generalizing the existing Jauge champ/row_id pattern).

- "valeur" (the comparison value, which could already reference another object's field via a "{{Objet.champ}}" string typed by hand) is now a "Valeur fixe" / "Donnée d'un autre objet" toggle — the dynamic mode shows an object dropdown and a dependent field dropdown, and picking from them reconstructs that internal reference string automatically (initFilterValuePickers()/updateFilterValueFromDynamic()). The underlying stored value and _resolve_filter_value's parsing are unchanged, so existing elements using the old typed syntax still load correctly and populate the pickers on open.

Guards against writing a literal "{{...}}" pair directly in the Jinja template source (caught by a real render error while building this — Jinja parses {{/}} anywhere in the file, including inside comments) by building that syntax from split string literals in JS instead.

Verified end to end: repeater panel renders the pickers, saving with a dynamic reference filters correctly against live data (current_level changing which row shows), and reloading pre-selects the right object/field in the dropdowns. Full suite green (89).

screens/widgets/registry.py

@@ -240,16 +240,16 @@ WIDGETS = {
             c_textarea("content", "Modèle d'affichage texte — utilise {{nom_du_champ}}", "content", default="{{nom}}", group="Contenu"),
             c_color("color", "Couleur du texte", "style:color", "#e8eaf0", group="Texte"),
             c_slider("font-size", "Taille du texte", "style:font-size", min=10, max=40, default=16, group="Texte"),
-            c_text("filtre_champ", "Filtrer : n'afficher que les lignes où ce champ",
-                   "attr:_filtre_champ", placeholder="ex. niveau", default="", group="Filtre"),
+            c_select("filtre_champ", "Filtrer : n'afficher que les lignes où ce champ",
+                     "attr:_filtre_champ", [("", "(sélectionner un objet d'abord)")], default="", group="Filtre"),
             c_select("filtre_operateur", "...est", "attr:_filtre_operateur", CONDITION_OPERATORS, default="egal", group="Filtre"),
-            c_text("filtre_valeur", "...cette valeur, ou {{NomObjet.champ}} pour comparer à une donnée qui change en cours de partie",
-                   "attr:_filtre_valeur", placeholder="ex. 3 ou {{Partie.niveau_courant}}", default="", group="Filtre"),
-            c_text("filtre2_champ", "ET (optionnel) : ce 2ᵉ champ",
-                   "attr:_filtre2_champ", placeholder="ex. parcour_id", default="", group="Filtre"),
+            c_text("filtre_valeur", "...cette valeur",
+                   "attr:_filtre_valeur", placeholder="ex. 3", default="", group="Filtre"),
+            c_select("filtre2_champ", "ET (optionnel) : ce 2ᵉ champ",
+                     "attr:_filtre2_champ", [("", "(sélectionner un objet d'abord)")], default="", group="Filtre"),
             c_select("filtre2_operateur", "...est", "attr:_filtre2_operateur", CONDITION_OPERATORS, default="egal", group="Filtre"),
-            c_text("filtre2_valeur", "...cette valeur, ou {{NomObjet.champ}}",
-                   "attr:_filtre2_valeur", placeholder="ex. 1 ou {{Partie.parcours_courant}}", default="", group="Filtre"),
+            c_text("filtre2_valeur", "...cette valeur",
+                   "attr:_filtre2_valeur", placeholder="ex. 1", default="", group="Filtre"),
         ],
     },
     "jauge": {