refactor: modernize code quality tooling with Ruff

- Replace black, isort, and flake8 with Ruff (all-in-one linter and formatter)
- Add comprehensive pyproject.toml configuration
- Simplify Makefile code quality targets
- Configure exclusions for venv/.venv in pyproject.toml
- Auto-fix 1,359 linting issues across codebase

Benefits:
- Much faster builds (Ruff is written in Rust)
- Single tool replaces multiple tools
- More comprehensive rule set (UP, B, C4, SIM, PIE, RET, Q)
- All configuration centralized in pyproject.toml
- Better import sorting and formatting consistency

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/v1/admin/vendors.py

@@ -4,7 +4,7 @@ Vendor management endpoints for admin.
 """
 
 import logging
-from typing import Optional
+from datetime import UTC
 
 from fastapi import APIRouter, Body, Depends, Path, Query
 from sqlalchemy import func
@@ -12,18 +12,21 @@ from sqlalchemy.orm import Session
 
 from app.api.deps import get_current_admin_api
 from app.core.database import get_db
-from app.exceptions import (ConfirmationRequiredException,
-                            VendorNotFoundException)
+from app.exceptions import ConfirmationRequiredException, VendorNotFoundException
 from app.services.admin_service import admin_service
 from app.services.stats_service import stats_service
 from models.database.user import User
 from models.database.vendor import Vendor
 from models.schema.stats import VendorStatsResponse
-from models.schema.vendor import (VendorCreate, VendorCreateResponse,
-                                  VendorDetailResponse, VendorListResponse,
-                                  VendorResponse, VendorTransferOwnership,
-                                  VendorTransferOwnershipResponse,
-                                  VendorUpdate)
+from models.schema.vendor import (
+    VendorCreate,
+    VendorCreateResponse,
+    VendorDetailResponse,
+    VendorListResponse,
+    VendorTransferOwnership,
+    VendorTransferOwnershipResponse,
+    VendorUpdate,
+)
 
 router = APIRouter(prefix="/vendors")
 logger = logging.getLogger(__name__)
@@ -126,9 +129,9 @@ def create_vendor_with_owner(
 def get_all_vendors_admin(
     skip: int = Query(0, ge=0),
     limit: int = Query(100, ge=1, le=1000),
-    search: Optional[str] = Query(None, description="Search by name or vendor code"),
-    is_active: Optional[bool] = Query(None),
-    is_verified: Optional[bool] = Query(None),
+    search: str | None = Query(None, description="Search by name or vendor code"),
+    is_active: bool | None = Query(None),
+    is_verified: bool | None = Query(None),
     db: Session = Depends(get_db),
     current_admin: User = Depends(get_current_admin_api),
 ):
@@ -282,7 +285,7 @@ def transfer_vendor_ownership(
     - `confirm_transfer`: Must be true
     - `transfer_reason`: Optional reason for audit trail
     """
-    from datetime import datetime, timezone
+    from datetime import datetime
 
     vendor = _get_vendor_by_identifier(db, vendor_identifier)
     vendor, old_owner, new_owner = admin_service.transfer_vendor_ownership(
@@ -304,7 +307,7 @@ def transfer_vendor_ownership(
             "username": new_owner.username,
             "email": new_owner.email,
         },
-        transferred_at=datetime.now(timezone.utc),
+        transferred_at=datetime.now(UTC),
         transfer_reason=transfer_data.transfer_reason,
     )