Migrate to FoundryVTT v13 AppV2 +

│ DataModels
│
│ - Reorganize DataModels into src/module/models/ (one .mjs per type)
│ - Create AppV2 actor/item sheets (HandlebarsApplicationMixin)…

src/module/applications/sheets/item-sheet.mjs

@@ -22,12 +22,14 @@ export default class TravellerItemSheet extends HandlebarsApplicationMixin(found
         },
     }
 
-    /** @override */
-    static PARTS = {
-        sheet: {
-            // template is dynamic — resolved in _prepareContext / _renderHTML
-            template: "",
-        },
+    /** Dynamic PARTS: template resolved per item type */
+    get PARTS() {
+        const type = this.document?.type ?? "item";
+        return {
+            sheet: {
+                template: `systems/mgt2/templates/items/${type}-sheet.html`,
+            },
+        };
     }
 
     /** Resolve template dynamically based on item type */
@@ -81,7 +83,7 @@ export default class TravellerItemSheet extends HandlebarsApplicationMixin(found
             systemFields: item.system.schema.fields,
             isEditable: this.isEditable,
             isGM: game.user.isGM,
-            config: CONFIG,
+            config: CONFIG.MGT2,
             settings: settings,
             containers: containers,
             computers: computers,
@@ -95,13 +97,16 @@ export default class TravellerItemSheet extends HandlebarsApplicationMixin(found
     /** @override — resolve the per-type template before rendering */
     async _renderHTML(context, options) {
         const templatePath = `systems/mgt2/templates/items/${this.document.type}-sheet.html`;
-        const html = await renderTemplate(templatePath, context);
+        const html = await foundry.applications.handlebars.renderTemplate(templatePath, context);
         return { sheet: html };
     }
 
     /** @override — put rendered HTML into the window content */
     _replaceHTML(result, content, options) {
         content.innerHTML = result.sheet;
+        // Inject theme class dynamically (can't use game.settings in static DEFAULT_OPTIONS)
+        const theme = game.settings.get("mgt2", "theme");
+        if (theme) this.element.classList.add(theme);
         this._activateTabGroups();
         this._bindItemEvents();
     }