feat(admin): separate platform CRUD from CMS, add entity selector macro

- Move platforms menu from CMS to Platform Admin section with create/edit
- Add platform create page, API endpoint, and service method
- Remove CMS-specific content from platform list and detail pages
- Create shared entity_selector + entity_selected_badge Jinja macros
- Create entity-selector.js generalizing store-selector.js for any entity
- Add Tom Select merchant filter to stores page with localStorage persistence
- Migrate store-products page to use shared macros (remove 53 lines of duped CSS)
- Fix broken icons: puzzle→puzzle-piece, building-storefront→store, language→translate, server→cube

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/tenancy/definition.py

@@ -164,20 +164,12 @@ tenancy_module = ModuleDefinition(
                         order=20,
                         is_mandatory=True,
                     ),
-                ],
-            ),
-            MenuSectionDefinition(
-                id="contentMgmt",
-                label_key="tenancy.menu.content_management",
-                icon="globe-alt",
-                order=70,
-                items=[
                     MenuItemDefinition(
                         id="platforms",
                         label_key="tenancy.menu.platforms",
                         icon="globe-alt",
                         route="/admin/platforms",
-                        order=10,
+                        order=5,
                     ),
                 ],
             ),