fix: apply all PR review agent findings (silent failures, type safety, test gaps)

Addresses issues found by 4 parallel review agents (code-reviewer,
silent-failure-hunter, type-design-analyzer, pr-test-analyzer).

Source fixes:
- core/utils.py: add public safe_display_url() (moved from tools/health.py)
- core/client.py: rename _redact_sensitive → redact_sensitive (public API)
- core/types.py: add SubscriptionData.__post_init__ for tz-aware datetime
  enforcement; remove 6 unused type aliases (SystemHealth, APIResponse, etc.)
- subscriptions/manager.py: add exc_info=True to both except-Exception blocks;
  add except ValueError break-on-config-error before retry loop; import
  redact_sensitive by new public name
- subscriptions/resources.py: re-raise in autostart_subscriptions() so
  ensure_subscriptions_started() doesn't permanently set _subscriptions_started
- subscriptions/diagnostics.py: except ToolError: raise before broad except;
  use safe_display_url() instead of raw URL slice
- tools/health.py: move _safe_display_url to core/utils; add exc_info=True;
  raise ToolError (not return dict) on ImportError
- tools/info.py: use get_args(INFO_ACTIONS) instead of INFO_ACTIONS.__args__
- tools/{array,docker,keys,notifications,rclone,storage,virtualization}.py:
  add Literal-vs-ALL_ACTIONS sync check at import time

Test fixes:
- test_health.py: import safe_display_url from core.utils; update
  test_diagnose_import_error_internal to expect ToolError (not error dict)
- test_storage.py: add 3 safe_get tests for zero/False/empty-string values
- test_subscription_manager.py: add TestCapLogContentSingleMassiveLine (2 tests)
- test_client.py: rename _redact_sensitive → redact_sensitive; add tests for
  new sensitive keys and is_cacheable explicit-keyword form

unraid_mcp/tools/keys.py

@@ -4,7 +4,7 @@ Provides the `unraid_keys` tool with 5 actions for listing, viewing,
 creating, updating, and deleting API keys.
 """
 
-from typing import Any, Literal
+from typing import Any, Literal, get_args
 
 from fastmcp import FastMCP
 
@@ -55,6 +55,14 @@ KEY_ACTIONS = Literal[
     "delete",
 ]
 
+if set(get_args(KEY_ACTIONS)) != ALL_ACTIONS:
+    _missing = ALL_ACTIONS - set(get_args(KEY_ACTIONS))
+    _extra = set(get_args(KEY_ACTIONS)) - ALL_ACTIONS
+    raise RuntimeError(
+        f"KEY_ACTIONS and ALL_ACTIONS are out of sync. "
+        f"Missing from Literal: {_missing or 'none'}. Extra in Literal: {_extra or 'none'}"
+    )
+
 
 def register_keys_tool(mcp: FastMCP) -> None:
     """Register the unraid_keys tool with the FastMCP instance."""