feat(storefront): homepage, module gating, widget protocol, i18n fixes

Storefront homepage & module gating:
- CMS owns storefront GET / (slug="home" with 3-tier resolution)
- Catalog loses GET / (keeps /products only)
- Store root redirect (GET / → /store/dashboard or /store/login)
- Route gating: non-core modules return 404 when disabled for platform
- Seed store default homepages per platform

Widget protocol for customer dashboard:
- StorefrontDashboardCard contract in widgets.py
- Widget aggregator get_storefront_dashboard_cards()
- Orders and Loyalty module widget providers
- Dashboard template renders contributed cards (no module names)

Landing template module-agnostic:
- CTAs driven by storefront_nav (not hardcoded module names)
- Header actions check nav item IDs (not enabled_modules)
- Remove hardcoded "Add Product" sidebar button
- Remove all enabled_modules checks from storefront templates

i18n fixes:
- Title placeholder resolution ({{store_name}}) for store default pages
- Storefront nav label_keys prefixed with module code
- Add storefront.account.* keys to 6 modules (en/fr/de/lb)
- Header/footer CMS pages use get_translated_title(current_language)
- Footer labels use i18n keys instead of hardcoded English

Icon cleanup:
- Standardize on map-pin (remove location-marker alias)
- Replace all location-marker references across templates and docs

Docs:
- Storefront builder vision proposal (6 phases)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/seed/create_default_content_pages.py

@@ -2097,6 +2097,49 @@ SHARED_PLATFORM_PAGES = [
 # ============================================================================
 
 
+STORE_DEFAULT_HOME = {
+    "slug": "home",
+    "title": "Welcome to {{store_name}}",
+    "title_translations": tt(
+        "Welcome to {{store_name}}",
+        "Bienvenue chez {{store_name}}",
+        "Willkommen bei {{store_name}}",
+        "Wëllkomm bei {{store_name}}",
+    ),
+    "content": """<div class="prose-content">
+    <h2>Welcome</h2>
+    <p>{{store_name}} is here to serve you. Browse our offerings and discover what we have for you.</p>
+</div>""",
+    "content_translations": tt(
+        # English
+        """<div class="prose-content">
+    <h2>Welcome</h2>
+    <p>{{store_name}} is here to serve you. Browse our offerings and discover what we have for you.</p>
+</div>""",
+        # French
+        """<div class="prose-content">
+    <h2>Bienvenue</h2>
+    <p>{{store_name}} est là pour vous servir. Découvrez nos offres et ce que nous avons pour vous.</p>
+</div>""",
+        # German
+        """<div class="prose-content">
+    <h2>Willkommen</h2>
+    <p>{{store_name}} ist für Sie da. Entdecken Sie unser Angebot.</p>
+</div>""",
+        # Luxembourgish
+        """<div class="prose-content">
+    <h2>Wëllkomm</h2>
+    <p>{{store_name}} ass fir Iech do. Entdeckt eist Angebot.</p>
+</div>""",
+    ),
+    "template": "default",
+    "meta_description": "Welcome to {{store_name}}",
+    "show_in_header": False,
+    "show_in_footer": False,
+    "display_order": 0,
+}
+
+
 STORE_DEFAULTS_COMMON = [
     {
         "slug": "about",
@@ -2753,6 +2796,12 @@ def create_default_pages(db: Session) -> None:
         #    Only for platforms that host stores (not wizard.lu main)
         # ------------------------------------------------------------------
         if platform.code != "main":
+            # Store homepage (slug="home")
+            if _create_page(db, platform.id, STORE_DEFAULT_HOME, is_platform_page=False):
+                created_count += 1
+            else:
+                skipped_count += 1
+
             for page_data in STORE_DEFAULTS_COMMON:
                 if _create_page(db, platform.id, page_data, is_platform_page=False):
                     created_count += 1