refactor: clean up legacy models and migrate remaining schemas

Delete empty stub files from models/database/:
- audit.py, backup.py, configuration.py, monitoring.py
- notification.py, payment.py, search.py, task.py

Delete re-export files:
- models/database/subscription.py → app.modules.billing.models
- models/database/architecture_scan.py → app.modules.dev_tools.models
- models/database/test_run.py → app.modules.dev_tools.models
- models/schema/subscription.py → app.modules.billing.schemas
- models/schema/marketplace.py (empty)
- models/schema/monitoring.py (empty)

Migrate schemas to canonical module locations:
- billing.py → app/modules/billing/schemas/
- vendor_product.py → app/modules/catalog/schemas/
- homepage_sections.py → app/modules/cms/schemas/

Keep as CORE (framework-level, used everywhere):
- models/schema/: admin, auth, base, company, email, image, media, team, vendor*
- models/database/: admin*, base, company, email, feature, media, platform*, user, vendor*

Update 30+ files to use canonical import locations.

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

app/modules/billing/schemas/__init__.py

@@ -32,24 +32,70 @@ from app.modules.billing.schemas.subscription import (
     CanAddTeamMemberResponse,
     FeatureCheckResponse,
 )
+from app.modules.billing.schemas.billing import (
+    # Subscription Tier Admin schemas
+    SubscriptionTierBase,
+    SubscriptionTierCreate,
+    SubscriptionTierUpdate,
+    SubscriptionTierResponse,
+    SubscriptionTierListResponse,
+    # Vendor Subscription schemas
+    VendorSubscriptionResponse,
+    VendorSubscriptionWithVendor,
+    VendorSubscriptionListResponse,
+    VendorSubscriptionCreate,
+    VendorSubscriptionUpdate,
+    # Billing History schemas
+    BillingHistoryResponse,
+    BillingHistoryWithVendor,
+    BillingHistoryListResponse,
+    # Checkout & Portal schemas
+    CheckoutRequest,
+    CheckoutResponse,
+    PortalSessionResponse,
+    # Stats schemas
+    SubscriptionStatsResponse,
+)
 
 __all__ = [
-    # Tier schemas
+    # Tier schemas (subscription.py)
     "TierFeatures",
     "TierLimits",
     "TierInfo",
-    # Subscription CRUD schemas
+    # Subscription CRUD schemas (subscription.py)
     "SubscriptionCreate",
     "SubscriptionUpdate",
     "SubscriptionResponse",
-    # Usage schemas
+    # Usage schemas (subscription.py)
     "SubscriptionUsage",
     "UsageSummary",
     "SubscriptionStatusResponse",
-    # Limit check schemas
+    # Limit check schemas (subscription.py)
     "LimitCheckResult",
     "CanCreateOrderResponse",
     "CanAddProductResponse",
     "CanAddTeamMemberResponse",
     "FeatureCheckResponse",
+    # Subscription Tier Admin schemas (billing.py)
+    "SubscriptionTierBase",
+    "SubscriptionTierCreate",
+    "SubscriptionTierUpdate",
+    "SubscriptionTierResponse",
+    "SubscriptionTierListResponse",
+    # Vendor Subscription schemas (billing.py)
+    "VendorSubscriptionResponse",
+    "VendorSubscriptionWithVendor",
+    "VendorSubscriptionListResponse",
+    "VendorSubscriptionCreate",
+    "VendorSubscriptionUpdate",
+    # Billing History schemas (billing.py)
+    "BillingHistoryResponse",
+    "BillingHistoryWithVendor",
+    "BillingHistoryListResponse",
+    # Checkout & Portal schemas (billing.py)
+    "CheckoutRequest",
+    "CheckoutResponse",
+    "PortalSessionResponse",
+    # Stats schemas (billing.py)
+    "SubscriptionStatsResponse",
 ]