refactor: comprehensive code review fixes across 31 files

Addresses all critical, high, medium, and low issues from full codebase
review. 494 tests pass, ruff clean, ty type-check clean.

Security:
- Add tool_error_handler context manager (exceptions.py) — standardised
  error handling, eliminates 11 bare except-reraise patterns
- Remove unused exception subclasses (ConfigurationError, UnraidAPIError,
  SubscriptionError, ValidationError, IdempotentOperationError)
- Harden GraphQL subscription query validator with allow-list and
  forbidden-keyword regex (diagnostics.py)
- Add input validation for rclone create_remote config_data: injection,
  path-traversal, and key-count limits (rclone.py)
- Validate notifications importance enum before GraphQL request (notifications.py)
- Sanitise HTTP/network/JSON error messages — no raw exception strings
  leaked to clients (client.py)
- Strip path/creds from displayed API URL via _safe_display_url (health.py)
- Enable Ruff S (bandit) rule category in pyproject.toml
- Harden container mutations to strict-only matching — no fuzzy/substring
  for destructive operations (docker.py)

Performance:
- Token-bucket rate limiter (90 tokens, 9 req/s) with 429 retry backoff (client.py)
- Lazy asyncio.Lock init via _get_client_lock() — fixes event-loop
  module-load crash (client.py)
- Double-checked locking in get_http_client() for fast-path (client.py)
- Short hex container ID fast-path skips list fetch (docker.py)
- Cap resource_data log content to 1 MB / 5,000 lines (manager.py)
- Reset reconnect counter after 30 s stable connection (manager.py)
- Move tail_lines validation to module level; enforce 10,000 line cap
  (storage.py, docker.py)
- force_terminal=True removed from logging RichHandler (logging.py)

Architecture:
- Register diagnostic tools in server startup (server.py)
- Move ALL_ACTIONS computation to module level in all tools
- Consolidate format_kb / format_bytes into shared core/utils.py
- Add _safe_get() helper in core/utils.py for nested dict traversal
- Extract _analyze_subscription_status() from health.py diagnose handler
- Validate required config at startup — fail fast with CRITICAL log (server.py)

Code quality:
- Remove ~90 lines of dead Rich formatting helpers from logging.py
- Remove dead self.websocket attribute from SubscriptionManager
- Remove dead setup_uvicorn_logging() wrapper
- Move _VALID_IMPORTANCE to module level (N806 fix)
- Add slots=True to all three dataclasses (SubscriptionData, SystemHealth, APIResponse)
- Fix None rendering as literal "None" string in info.py summaries
- Change fuzzy-match log messages from INFO to DEBUG (docker.py)
- UTC-aware datetimes throughout (manager.py, diagnostics.py)

Infrastructure:
- Upgrade base image python:3.11-slim → python:3.12-slim (Dockerfile)
- Add non-root appuser (UID/GID 1000) with HEALTHCHECK (Dockerfile)
- Add read_only, cap_drop: ALL, tmpfs /tmp to docker-compose.yml
- Single-source version via importlib.metadata (pyproject.toml → __init__.py)
- Add open_timeout to all websockets.connect() calls

Tests:
- Update error message matchers to match sanitised messages (test_client.py)
- Fix patch targets for UNRAID_API_URL → utils module (test_subscriptions.py)
- Fix importance="info" → importance="normal" (test_notifications.py, http_layer)
- Fix naive datetime fixtures → UTC-aware (test_subscriptions.py)

Co-authored-by: Claude <claude@anthropic.com>

unraid_mcp/subscriptions/utils.py

@@ -2,7 +2,34 @@
 
 import ssl as _ssl
 
-from ..config.settings import UNRAID_VERIFY_SSL
+from ..config.settings import UNRAID_API_URL, UNRAID_VERIFY_SSL
+
+
+def build_ws_url() -> str:
+    """Build a WebSocket URL from the configured UNRAID_API_URL.
+
+    Converts http(s) scheme to ws(s) and ensures /graphql path suffix.
+
+    Returns:
+        The WebSocket URL string (e.g. "wss://10.1.0.2:31337/graphql").
+
+    Raises:
+        ValueError: If UNRAID_API_URL is not configured.
+    """
+    if not UNRAID_API_URL:
+        raise ValueError("UNRAID_API_URL is not configured")
+
+    if UNRAID_API_URL.startswith("https://"):
+        ws_url = "wss://" + UNRAID_API_URL[len("https://") :]
+    elif UNRAID_API_URL.startswith("http://"):
+        ws_url = "ws://" + UNRAID_API_URL[len("http://") :]
+    else:
+        ws_url = UNRAID_API_URL
+
+    if not ws_url.endswith("/graphql"):
+        ws_url = ws_url.rstrip("/") + "/graphql"
+
+    return ws_url
 
 
 def build_ws_ssl_context(ws_url: str) -> _ssl.SSLContext | None: