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/auth.py

@@ -3,10 +3,8 @@
 Authentication and authorization specific exceptions.
 """
 
-from typing import Optional
 
-from .base import (AuthenticationException, AuthorizationException,
-                   ConflictException)
+from .base import AuthenticationException, AuthorizationException, ConflictException
 
 
 class InvalidCredentialsException(AuthenticationException):
@@ -45,7 +43,7 @@ class InsufficientPermissionsException(AuthorizationException):
     def __init__(
         self,
         message: str = "Insufficient permissions for this action",
-        required_permission: Optional[str] = None,
+        required_permission: str | None = None,
     ):
         details = {}
         if required_permission:
@@ -84,7 +82,7 @@ class UserAlreadyExistsException(ConflictException):
     def __init__(
         self,
         message: str = "User already exists",
-        field: Optional[str] = None,
+        field: str | None = None,
     ):
         details = {}
         if field: