fix(lint): pin ruff version, add pre-commit hook, fix all lint errors

- Pin ruff==0.8.4 in requirements-dev.txt (was >=0.8.4, CI got newer
  version with different import sorting rules)
- Add ruff to .pre-commit-config.yaml with --fix to auto-sort imports
  on commit (prevents PyCharm import reordering from reaching CI)
- Fix I001 import sorting in 6 files
- Fix F401 unused import (sqlalchemy.Numeric in subscription.py)
- Fix noqa false positive in validate_architecture.py comment

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/analytics/services/stats_service.py

@@ -21,7 +21,10 @@ from sqlalchemy.orm import Session
 from app.modules.catalog.models import Product  # IMPORT-002
 from app.modules.customers.models.customer import Customer  # IMPORT-002
 from app.modules.inventory.models import Inventory  # IMPORT-002
-from app.modules.marketplace.models import MarketplaceImportJob, MarketplaceProduct  # IMPORT-002
+from app.modules.marketplace.models import (  # IMPORT-002
+    MarketplaceImportJob,
+    MarketplaceProduct,
+)
 from app.modules.orders.models import Order  # IMPORT-002
 from app.modules.tenancy.exceptions import (
     AdminOperationException,

app/modules/billing/models/subscription.py

@@ -22,7 +22,6 @@ from sqlalchemy import (
     ForeignKey,
     Index,
     Integer,
-    Numeric,
     String,
     Text,
 )

app/modules/billing/schemas/__init__.py

@@ -21,8 +21,6 @@ from app.modules.billing.schemas.billing import (
     CancelRequest,
     CancelResponse,
     CategoryListResponse,
-    ChangeTierRequest as BillingChangeTierRequest,
-    ChangeTierResponse as BillingChangeTierResponse,
     # Checkout & Portal schemas
     CheckoutRequest,
     CheckoutResponse,
@@ -56,12 +54,18 @@ from app.modules.billing.schemas.billing import (
     SubscriptionTierListResponse,
     SubscriptionTierResponse,
     SubscriptionTierUpdate,
-    TierListResponse,
-    TierResponse,
     # Subscription Tier Admin schemas
     TierFeatureLimitEntry,
+    TierListResponse,
+    TierResponse,
     UpcomingInvoiceResponse,
 )
+from app.modules.billing.schemas.billing import (
+    ChangeTierRequest as BillingChangeTierRequest,
+)
+from app.modules.billing.schemas.billing import (
+    ChangeTierResponse as BillingChangeTierResponse,
+)
 from app.modules.billing.schemas.subscription import (
     ChangeTierRequest,
     ChangeTierResponse,

app/modules/messaging/routes/api/storefront.py

@@ -32,7 +32,10 @@ from app.modules.messaging.exceptions import (
     ConversationClosedException,
     ConversationNotFoundException,
 )
-from app.modules.messaging.models.message import ConversationType, ParticipantType  # API-007
+from app.modules.messaging.models.message import (  # API-007
+    ConversationType,
+    ParticipantType,
+)
 from app.modules.messaging.schemas import (
     ConversationDetailResponse,
     ConversationListResponse,

app/modules/monitoring/models/__init__.py

@@ -5,10 +5,9 @@ Monitoring module database models.
 Provides monitoring-related models including capacity snapshots.
 """
 
-from app.modules.monitoring.models.capacity_snapshot import CapacitySnapshot
-
 # Admin notification and logging models
 from app.modules.messaging.models import AdminNotification
+from app.modules.monitoring.models.capacity_snapshot import CapacitySnapshot
 from app.modules.tenancy.models import PlatformAlert
 
 __all__ = [

app/modules/monitoring/services/__init__.py

@@ -9,14 +9,14 @@ from app.modules.monitoring.services.admin_audit_service import (
     AdminAuditService,
     admin_audit_service,
 )
-from app.modules.monitoring.services.capacity_forecast_service import (
-    CapacityForecastService,
-    capacity_forecast_service,
-)
 from app.modules.monitoring.services.background_tasks_service import (
     BackgroundTasksService,
     background_tasks_service,
 )
+from app.modules.monitoring.services.capacity_forecast_service import (
+    CapacityForecastService,
+    capacity_forecast_service,
+)
 from app.modules.monitoring.services.log_service import (
     LogService,
     log_service,