feat: complete analytics module self-containment

Migrate analytics module to fully self-contained structure:

- routes/api/vendor.py - API endpoints
- routes/pages/vendor.py - Page routes with full implementation
- services/stats_service.py - Business logic (moved from app/services)
- services/usage_service.py - Usage tracking (moved from app/services)
- schemas/stats.py - Pydantic schemas (moved from models/schema)
- models/__init__.py - Model exports
- templates/analytics/vendor/ - Templates (moved from app/templates)
- static/vendor/js/ - JavaScript (moved from static/vendor)
- locales/ - Translations (en, de, fr, lu)
- exceptions.py - Module exceptions

Removed legacy files:
- app/modules/analytics/routes/vendor.py (replaced by routes/pages/)
- static/admin/js/analytics.js (unused)

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

app/modules/analytics/routes/__init__.py

@@ -6,8 +6,9 @@ This module provides functions to register analytics routes
 with module-based access control.
 
 NOTE: Routers are NOT auto-imported to avoid circular dependencies.
-Import directly from vendor.py as needed:
-  from app.modules.analytics.routes.vendor import vendor_router
+Import directly from api/ or pages/ as needed:
+  from app.modules.analytics.routes.api import vendor_router as vendor_api_router
+  from app.modules.analytics.routes.pages import vendor_router as vendor_page_router
 
 Note: Analytics module has no admin routes - admin uses dashboard.
 """
@@ -15,12 +16,15 @@ Note: Analytics module has no admin routes - admin uses dashboard.
 # Routers are imported on-demand to avoid circular dependencies
 # Do NOT add auto-imports here
 
-__all__ = ["vendor_router"]
+__all__ = ["vendor_api_router", "vendor_page_router"]
 
 
 def __getattr__(name: str):
     """Lazy import routers to avoid circular dependencies."""
-    if name == "vendor_router":
-        from app.modules.analytics.routes.vendor import vendor_router
+    if name == "vendor_api_router":
+        from app.modules.analytics.routes.api import vendor_router
+        return vendor_router
+    elif name == "vendor_page_router":
+        from app.modules.analytics.routes.pages import vendor_router
         return vendor_router
     raise AttributeError(f"module {__name__!r} has no attribute {name!r}")