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/schemas/__init__.py

@@ -0,0 +1,58 @@
+# app/modules/analytics/schemas/__init__.py
+"""
+Analytics module Pydantic schemas.
+
+This is the canonical location for analytics schemas.
+"""
+
+from app.modules.analytics.schemas.stats import (
+    StatsResponse,
+    MarketplaceStatsResponse,
+    ImportStatsResponse,
+    UserStatsResponse,
+    VendorStatsResponse,
+    ProductStatsResponse,
+    PlatformStatsResponse,
+    OrderStatsBasicResponse,
+    AdminDashboardResponse,
+    VendorProductStats,
+    VendorOrderStats,
+    VendorCustomerStats,
+    VendorRevenueStats,
+    VendorInfo,
+    VendorDashboardStatsResponse,
+    VendorAnalyticsImports,
+    VendorAnalyticsCatalog,
+    VendorAnalyticsInventory,
+    VendorAnalyticsResponse,
+    ValidatorStats,
+    CodeQualityDashboardStatsResponse,
+    CustomerStatsResponse,
+    OrderStatsResponse,
+)
+
+__all__ = [
+    "StatsResponse",
+    "MarketplaceStatsResponse",
+    "ImportStatsResponse",
+    "UserStatsResponse",
+    "VendorStatsResponse",
+    "ProductStatsResponse",
+    "PlatformStatsResponse",
+    "OrderStatsBasicResponse",
+    "AdminDashboardResponse",
+    "VendorProductStats",
+    "VendorOrderStats",
+    "VendorCustomerStats",
+    "VendorRevenueStats",
+    "VendorInfo",
+    "VendorDashboardStatsResponse",
+    "VendorAnalyticsImports",
+    "VendorAnalyticsCatalog",
+    "VendorAnalyticsInventory",
+    "VendorAnalyticsResponse",
+    "ValidatorStats",
+    "CodeQualityDashboardStatsResponse",
+    "CustomerStatsResponse",
+    "OrderStatsResponse",
+]