Refactor code for improved readability and consistency

- Reformatted function signatures in `organization_service.py` and `task_service.py` for better alignment.
- Updated import statements across multiple files for consistency and organization.
- Enhanced test files by improving formatting and ensuring consistent use of async session factories.
- Added type hints and improved type safety in various service and test files.
- Adjusted `pyproject.toml` to include configuration for isort, mypy, and ruff for better code quality checks.
- Cleaned up unused imports and organized existing ones in several test files.

app/core/cache.py

@@ -1,17 +1,18 @@
 """Redis cache utilities and availability tracking."""
+
 from __future__ import annotations
 
 import asyncio
 import json
 import logging
-from typing import Any, Awaitable, Callable, Optional
+from collections.abc import Awaitable, Callable
+from typing import Any
 
 import redis.asyncio as redis
+from app.core.config import settings
 from redis.asyncio.client import Redis
 from redis.exceptions import RedisError
 
-from app.core.config import settings
-
 logger = logging.getLogger(__name__)
 
 
@@ -44,7 +45,9 @@ class RedisCacheManager:
         async with self._lock:
             if self._client is not None:
                 return
-            self._client = redis.from_url(settings.redis_url, encoding="utf-8", decode_responses=False)
+            self._client = redis.from_url(
+                settings.redis_url, encoding="utf-8", decode_responses=False
+            )
             await self._refresh_availability()
 
     async def shutdown(self) -> None:
@@ -59,7 +62,9 @@ class RedisCacheManager:
             return
         async with self._lock:
             if self._client is None:
-                self._client = redis.from_url(settings.redis_url, encoding="utf-8", decode_responses=False)
+                self._client = redis.from_url(
+                    settings.redis_url, encoding="utf-8", decode_responses=False
+                )
             await self._refresh_availability()
 
     async def _refresh_availability(self) -> None:
@@ -95,7 +100,7 @@ async def shutdown_cache() -> None:
     await cache_manager.shutdown()
 
 
-def get_cache_client() -> Optional[Redis]:
+def get_cache_client() -> Redis | None:
     """Expose the active Redis client for dependency injection."""
     return cache_manager.get_client()
 
@@ -113,12 +118,17 @@ async def read_json(client: Redis, key: str) -> Any | None:
     cache_manager.mark_available()
     try:
         return json.loads(raw.decode("utf-8"))
-    except (UnicodeDecodeError, json.JSONDecodeError) as exc:  # pragma: no cover - malformed payloads
+    except (
+        UnicodeDecodeError,
+        json.JSONDecodeError,
+    ) as exc:  # pragma: no cover - malformed payloads
         logger.warning("Discarding malformed cache entry %s: %s", key, exc)
         return None
 
 
-async def write_json(client: Redis, key: str, value: Any, ttl_seconds: int, backoff_ms: int) -> None:
+async def write_json(
+    client: Redis, key: str, value: Any, ttl_seconds: int, backoff_ms: int
+) -> None:
     """Serialize data to JSON and store it with TTL using retry/backoff."""
     payload = json.dumps(value, separators=(",", ":"), ensure_ascii=True).encode("utf-8")