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/api/__init__.py

@@ -0,0 +1,11 @@
+# app/modules/analytics/routes/api/__init__.py
+"""
+Analytics module API routes.
+
+Provides REST API endpoints for analytics and reporting:
+- Vendor API: Vendor-scoped analytics data
+"""
+
+from app.modules.analytics.routes.api.vendor import router as vendor_router
+
+__all__ = ["vendor_router"]

app/modules/analytics/routes/api/vendor.py

@@ -0,0 +1,56 @@
+# app/modules/analytics/routes/api/vendor.py
+"""
+Vendor Analytics API
+
+Vendor Context: Uses token_vendor_id from JWT token (authenticated vendor API pattern).
+The get_current_vendor_api dependency guarantees token_vendor_id is present.
+
+Feature Requirements:
+- basic_reports: Basic analytics (Essential tier)
+- analytics_dashboard: Advanced analytics (Business tier)
+"""
+
+import logging
+
+from fastapi import APIRouter, Depends, Query
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_current_vendor_api, get_db, require_module_access
+from app.core.feature_gate import RequireFeature
+from app.modules.analytics.services import stats_service
+from app.modules.analytics.schemas import (
+    VendorAnalyticsCatalog,
+    VendorAnalyticsImports,
+    VendorAnalyticsInventory,
+    VendorAnalyticsResponse,
+)
+from models.database.feature import FeatureCode
+from models.database.user import User
+
+router = APIRouter(
+    dependencies=[Depends(require_module_access("analytics"))],
+)
+logger = logging.getLogger(__name__)
+
+
+@router.get("", response_model=VendorAnalyticsResponse)
+def get_vendor_analytics(
+    period: str = Query("30d", description="Time period: 7d, 30d, 90d, 1y"),
+    current_user: User = Depends(get_current_vendor_api),
+    db: Session = Depends(get_db),
+    _: None = Depends(RequireFeature(FeatureCode.BASIC_REPORTS, FeatureCode.ANALYTICS_DASHBOARD)),
+):
+    """Get vendor analytics data for specified time period."""
+    data = stats_service.get_vendor_analytics(db, current_user.token_vendor_id, period)
+
+    return VendorAnalyticsResponse(
+        period=data["period"],
+        start_date=data["start_date"],
+        imports=VendorAnalyticsImports(count=data["imports"]["count"]),
+        catalog=VendorAnalyticsCatalog(
+            products_added=data["catalog"]["products_added"]
+        ),
+        inventory=VendorAnalyticsInventory(
+            total_locations=data["inventory"]["total_locations"]
+        ),
+    )