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/exceptions/handler.py

@@ -11,7 +11,6 @@ This module provides classes and functions for:
 """
 
 import logging
-from typing import Union
 
 from fastapi import HTTPException, Request
 from fastapi.exceptions import RequestValidationError
@@ -280,7 +279,7 @@ def setup_exception_handlers(app):
                 request=request,
                 status_code=404,
                 error_code="ENDPOINT_NOT_FOUND",
-                message=f"The page you're looking for doesn't exist or has been moved.",
+                message="The page you're looking for doesn't exist or has been moved.",
                 details={"path": request.url.path},
                 show_debug=True,
             )
@@ -364,10 +363,10 @@ def _redirect_to_login(request: Request) -> RedirectResponse:
     if context_type == RequestContext.ADMIN:
         logger.debug("Redirecting to /admin/login")
         return RedirectResponse(url="/admin/login", status_code=302)
-    elif context_type == RequestContext.VENDOR_DASHBOARD:
+    if context_type == RequestContext.VENDOR_DASHBOARD:
         logger.debug("Redirecting to /vendor/login")
         return RedirectResponse(url="/vendor/login", status_code=302)
-    elif context_type == RequestContext.SHOP:
+    if context_type == RequestContext.SHOP:
         # For shop context, redirect to shop login (customer login)
         # Calculate base_url for proper routing (supports domain, subdomain, and path-based access)
         vendor = getattr(request.state, "vendor", None)
@@ -390,10 +389,9 @@ def _redirect_to_login(request: Request) -> RedirectResponse:
         login_url = f"{base_url}shop/account/login"
         logger.debug(f"Redirecting to {login_url}")
         return RedirectResponse(url=login_url, status_code=302)
-    else:
-        # Fallback to root for unknown contexts
-        logger.debug("Unknown context, redirecting to /")
-        return RedirectResponse(url="/", status_code=302)
+    # Fallback to root for unknown contexts
+    logger.debug("Unknown context, redirecting to /")
+    return RedirectResponse(url="/", status_code=302)
 
 
 # Utility functions for common exception scenarios