feat: complete dynamic menu system across all frontends

- Add "Merchant Frontend" tab to admin menu-config page
- Merchant render endpoint now respects AdminMenuConfig visibility
  via get_merchant_primary_platform_id() platform resolution
- New store menu render endpoint (GET /store/core/menu/render/store)
  with platform-scoped visibility and store_code interpolation
- Store sidebar migrated from hardcoded Jinja2 macros to dynamic
  Alpine.js x-for rendering with loading skeleton and fallback
- Store init-alpine.js: add loadMenuConfig(), expandSectionForCurrentPage()
- Include store page route fixes, login template updates, and tests

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

app/modules/core/static/store/js/init-alpine.js

@@ -21,14 +21,20 @@ function getStoreSidebarSectionsFromStorage() {
     } catch (e) {
         console.warn('[STORE INIT-ALPINE] Failed to load sidebar state from localStorage:', e);
     }
-    // Default: all sections open
-    return {
-        products: true,
-        sales: true,
-        customers: true,
-        shop: true,
-        account: true
-    };
+    // Default: empty (populated dynamically from API response)
+    return {};
+}
+
+function findSectionForPage(menuData, pageId) {
+    if (!menuData?.sections) return null;
+    for (const section of menuData.sections) {
+        for (const item of (section.items || [])) {
+            if (item.id === pageId) {
+                return section.id;
+            }
+        }
+    }
+    return null;
 }
 
 function saveStoreSidebarSectionsToStorage(sections) {
@@ -51,6 +57,10 @@ function data() {
         store: null,
         storeCode: null,
 
+        // Dynamic menu state
+        menuData: null,
+        menuLoading: false,
+
         // Sidebar collapsible sections state
         openSections: getStoreSidebarSectionsFromStorage(),
 
@@ -81,8 +91,9 @@ function data() {
                 this.dark = true;
             }
 
-            // Load store info
+            // Load store info and dynamic menu
             this.loadStoreInfo();
+            this.loadMenuConfig();
 
             // Save last visited page (for redirect after login)
             // Exclude login, logout, onboarding, error pages
@@ -111,6 +122,38 @@ function data() {
             }
         },
 
+        async loadMenuConfig() {
+            if (this.menuData || this.menuLoading) return;
+            if (typeof apiClient === 'undefined') return;
+            if (!localStorage.getItem('store_token')) return;
+
+            this.menuLoading = true;
+            try {
+                this.menuData = await apiClient.get('/store/core/menu/render/store');
+                // Initialize section open state from response
+                for (const section of (this.menuData?.sections || [])) {
+                    if (this.openSections[section.id] === undefined) {
+                        this.openSections[section.id] = true;
+                    }
+                }
+                saveStoreSidebarSectionsToStorage(this.openSections);
+                this.expandSectionForCurrentPage();
+            } catch (e) {
+                console.debug('Menu config not loaded, using fallback:', e?.message || e);
+            } finally {
+                this.menuLoading = false;
+            }
+        },
+
+        expandSectionForCurrentPage() {
+            if (!this.menuData) return;
+            const sectionId = findSectionForPage(this.menuData, this.currentPage);
+            if (sectionId && !this.openSections[sectionId]) {
+                this.openSections[sectionId] = true;
+                saveStoreSidebarSectionsToStorage(this.openSections);
+            }
+        },
+
         toggleSideMenu() {
             this.isSideMenuOpen = !this.isSideMenuOpen;
         },