refactor: migrate templates and static files to self-contained modules

Templates Migration:
- Migrate admin templates to modules (tenancy, billing, monitoring, marketplace, etc.)
- Migrate vendor templates to modules (tenancy, billing, orders, messaging, etc.)
- Migrate storefront templates to modules (catalog, customers, orders, cart, checkout, cms)
- Migrate public templates to modules (billing, marketplace, cms)
- Keep shared templates in app/templates/ (base.html, errors/, partials/, macros/)
- Migrate letzshop partials to marketplace module

Static Files Migration:
- Migrate admin JS to modules: tenancy (23 files), core (5 files), monitoring (1 file)
- Migrate vendor JS to modules: tenancy (4 files), core (2 files)
- Migrate shared JS: vendor-selector.js to core, media-picker.js to cms
- Migrate storefront JS: storefront-layout.js to core
- Keep framework JS in static/ (api-client, utils, money, icons, log-config, lib/)
- Update all template references to use module_static paths

Naming Consistency:
- Rename static/platform/ to static/public/
- Rename app/templates/platform/ to app/templates/public/
- Update all extends and static references

Documentation:
- Update module-system.md with shared templates documentation
- Update frontend-structure.md with new module JS organization

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/messaging/routes/pages/admin.py

@@ -0,0 +1,110 @@
+# app/modules/messaging/routes/pages/admin.py
+"""
+Messaging Admin Page Routes (HTML rendering).
+
+Admin pages for messaging management:
+- Notifications
+- Messages list
+- Conversation detail
+- Email templates
+"""
+
+from fastapi import APIRouter, Depends, Path, Request
+from fastapi.responses import HTMLResponse
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, require_menu_access
+from app.modules.core.utils.page_context import get_admin_context
+from app.templates_config import templates
+from models.database.admin_menu_config import FrontendType
+from models.database.user import User
+
+router = APIRouter()
+
+
+# ============================================================================
+# NOTIFICATIONS ROUTES
+# ============================================================================
+
+
+@router.get("/notifications", response_class=HTMLResponse, include_in_schema=False)
+async def admin_notifications_page(
+    request: Request,
+    current_user: User = Depends(
+        require_menu_access("notifications", FrontendType.ADMIN)
+    ),
+    db: Session = Depends(get_db),
+):
+    """
+    Render notifications management page.
+    Shows all admin notifications and platform alerts.
+    """
+    return templates.TemplateResponse(
+        "messaging/admin/notifications.html",
+        get_admin_context(request, current_user),
+    )
+
+
+# ============================================================================
+# MESSAGING ROUTES
+# ============================================================================
+
+
+@router.get("/messages", response_class=HTMLResponse, include_in_schema=False)
+async def admin_messages_page(
+    request: Request,
+    current_user: User = Depends(require_menu_access("messages", FrontendType.ADMIN)),
+    db: Session = Depends(get_db),
+):
+    """
+    Render messaging page.
+    Shows all conversations (admin_vendor and admin_customer channels).
+    """
+    return templates.TemplateResponse(
+        "messaging/admin/messages.html",
+        get_admin_context(request, current_user),
+    )
+
+
+@router.get(
+    "/messages/{conversation_id}",
+    response_class=HTMLResponse,
+    include_in_schema=False,
+)
+async def admin_conversation_detail_page(
+    request: Request,
+    conversation_id: int = Path(..., description="Conversation ID"),
+    current_user: User = Depends(require_menu_access("messages", FrontendType.ADMIN)),
+    db: Session = Depends(get_db),
+):
+    """
+    Render conversation detail page.
+    Shows the full conversation thread with messages.
+    """
+    return templates.TemplateResponse(
+        "messaging/admin/messages.html",
+        get_admin_context(request, current_user, conversation_id=conversation_id),
+    )
+
+
+# ============================================================================
+# EMAIL TEMPLATES ROUTES
+# ============================================================================
+
+
+@router.get("/email-templates", response_class=HTMLResponse, include_in_schema=False)
+async def admin_email_templates_page(
+    request: Request,
+    current_user: User = Depends(
+        require_menu_access("email-templates", FrontendType.ADMIN)
+    ),
+    db: Session = Depends(get_db),
+):
+    """
+    Render email templates management page.
+    Shows all platform email templates with edit capabilities.
+    """
+    return templates.TemplateResponse(
+        "messaging/admin/email-templates.html",
+        get_admin_context(request, current_user),
+    )