feat: complete CMS as fully autonomous self-contained module

Transform CMS from a thin wrapper into a fully self-contained module with
all code living within app/modules/cms/:

Module Structure:
- models/: ContentPage model (canonical location with dynamic discovery)
- schemas/: Pydantic schemas for API validation
- services/: ContentPageService business logic
- exceptions/: Module-specific exceptions
- routes/api/: REST API endpoints (admin, vendor, shop)
- routes/pages/: HTML page routes (admin, vendor)
- templates/cms/: Jinja2 templates (namespaced)
- static/: JavaScript files (admin/vendor)
- locales/: i18n translations (en, fr, de, lb)

Key Changes:
- Move ContentPage model to module with dynamic model discovery
- Create Pydantic schemas package for request/response validation
- Extract API routes from app/api/v1/*/ to module
- Extract page routes from admin_pages.py/vendor_pages.py to module
- Move static JS files to module with dedicated mount point
- Update templates to use cms_static for module assets
- Add module static file mounting in main.py
- Delete old scattered files (no shims - hard errors on old imports)

This establishes the pattern for migrating other modules to be
fully autonomous and independently deployable.

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

main.py

@@ -63,6 +63,10 @@ from app.exceptions.handler import setup_exception_handlers
 
 # Import page routers
 from app.routes import admin_pages, platform_pages, shop_pages, vendor_pages
+
+# Import CMS module page routers (self-contained module)
+from app.modules.cms.routes.pages import admin_router as cms_admin_pages
+from app.modules.cms.routes.pages import vendor_router as cms_vendor_pages
 from app.utils.i18n import get_jinja2_globals
 from middleware.context import ContextMiddleware
 from middleware.language import LanguageMiddleware
@@ -180,6 +184,19 @@ if STATIC_DIR.exists():
 else:
     logger.warning(f"Static directory not found at {STATIC_DIR}")
 
+# Mount module static files (self-contained modules)
+MODULES_DIR = BASE_DIR / "app" / "modules"
+if MODULES_DIR.exists():
+    for module_dir in sorted(MODULES_DIR.iterdir()):
+        if not module_dir.is_dir():
+            continue
+        module_static = module_dir / "static"
+        if module_static.exists():
+            module_name = module_dir.name
+            mount_path = f"/static/modules/{module_name}"
+            app.mount(mount_path, StaticFiles(directory=str(module_static)), name=f"{module_name}_static")
+            logger.info(f"Mounted module static files: {mount_path} -> {module_static}")
+
 # Mount uploads directory for user-uploaded media files
 UPLOADS_DIR = BASE_DIR / "uploads"
 if UPLOADS_DIR.exists():
@@ -301,6 +318,13 @@ app.include_router(
     admin_pages.router, prefix="/admin", tags=["admin-pages"], include_in_schema=False
 )
 
+# CMS module admin pages (self-contained module)
+# NOTE: These routes are specific (/content-pages/*) so they won't conflict
+logger.info("Registering CMS admin page routes: /admin/content-pages/*")
+app.include_router(
+    cms_admin_pages, prefix="/admin", tags=["cms-admin-pages"], include_in_schema=False
+)
+
 # Vendor management pages (dashboard, products, orders, etc.)
 logger.info("Registering vendor page routes: /vendor/{code}/*")
 app.include_router(
@@ -310,6 +334,13 @@ app.include_router(
     include_in_schema=False,
 )
 
+# CMS module vendor pages (self-contained module)
+# NOTE: Includes catch-all /{vendor_code}/{slug} - must be registered AFTER vendor_pages
+logger.info("Registering CMS vendor page routes: /vendor/{code}/content-pages/*")
+app.include_router(
+    cms_vendor_pages, prefix="/vendor", tags=["cms-vendor-pages"], include_in_schema=False
+)
+
 # Customer shop pages - Register at TWO prefixes:
 # 1. /shop/* (for subdomain/custom domain modes)
 # 2. /vendors/{code}/shop/* (for path-based development mode)
@@ -345,7 +376,7 @@ async def vendor_root_path(
         raise HTTPException(status_code=404, detail=f"Vendor '{vendor_code}' not found")
 
     from app.routes.shop_pages import get_shop_context
-    from app.services.content_page_service import content_page_service
+    from app.modules.cms.services import content_page_service
 
     # Get platform_id (use platform from context or default to 1 for OMS)
     platform_id = platform.id if platform else 1