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/services/stats_service.py

@@ -11,7 +11,7 @@ This module provides:
 
 import logging
 from datetime import datetime, timedelta
-from typing import Any, Dict, List
+from typing import Any
 
 from sqlalchemy import func
 from sqlalchemy.orm import Session
@@ -36,7 +36,7 @@ class StatsService:
     # VENDOR-SPECIFIC STATISTICS
     # ========================================================================
 
-    def get_vendor_stats(self, db: Session, vendor_id: int) -> Dict[str, Any]:
+    def get_vendor_stats(self, db: Session, vendor_id: int) -> dict[str, Any]:
         """
         Get statistics for a specific vendor.
 
@@ -177,7 +177,7 @@ class StatsService:
 
     def get_vendor_analytics(
         self, db: Session, vendor_id: int, period: str = "30d"
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         """
         Get a specific vendor analytics for a time period.
 
@@ -283,7 +283,7 @@ class StatsService:
     # SYSTEM-WIDE STATISTICS (ADMIN)
     # ========================================================================
 
-    def get_comprehensive_stats(self, db: Session) -> Dict[str, Any]:
+    def get_comprehensive_stats(self, db: Session) -> dict[str, Any]:
         """
         Get comprehensive system statistics for admin dashboard.
 
@@ -333,7 +333,7 @@ class StatsService:
                 reason=f"Database query failed: {str(e)}",
             )
 
-    def get_marketplace_breakdown_stats(self, db: Session) -> List[Dict[str, Any]]:
+    def get_marketplace_breakdown_stats(self, db: Session) -> list[dict[str, Any]]:
         """
         Get statistics broken down by marketplace.
 
@@ -382,7 +382,7 @@ class StatsService:
                 reason=f"Database query failed: {str(e)}",
             )
 
-    def get_user_statistics(self, db: Session) -> Dict[str, Any]:
+    def get_user_statistics(self, db: Session) -> dict[str, Any]:
         """
         Get user statistics for admin dashboard.
 
@@ -416,7 +416,7 @@ class StatsService:
                 operation="get_user_statistics", reason="Database query failed"
             )
 
-    def get_import_statistics(self, db: Session) -> Dict[str, Any]:
+    def get_import_statistics(self, db: Session) -> dict[str, Any]:
         """
         Get import job statistics.
 
@@ -457,7 +457,7 @@ class StatsService:
                 "success_rate": 0,
             }
 
-    def get_order_statistics(self, db: Session) -> Dict[str, Any]:
+    def get_order_statistics(self, db: Session) -> dict[str, Any]:
         """
         Get order statistics.
 
@@ -472,7 +472,7 @@ class StatsService:
         """
         return {"total_orders": 0, "pending_orders": 0, "completed_orders": 0}
 
-    def get_product_statistics(self, db: Session) -> Dict[str, Any]:
+    def get_product_statistics(self, db: Session) -> dict[str, Any]:
         """
         Get product statistics.
 
@@ -548,7 +548,7 @@ class StatsService:
             .count()
         )
 
-    def _get_inventory_statistics(self, db: Session) -> Dict[str, int]:
+    def _get_inventory_statistics(self, db: Session) -> dict[str, int]:
         """
         Get inventory-related statistics.