- Add GET /api/vehicles/inventory-stats endpoint that groups inventory vehicles by macro-region, city, brand, type, model, and batch
- Add RegionalInventoryStats type and fetchInventoryStats API function
- Add full inventory statistics section with region/model tabs, filters, desktop table, and mobile views
- Add modal filters (plate number, model, brand, location search) to vehicle detail modal
- Update modal header to support title field for contextual naming
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>