refactor(search): pre-push review fixes for PR #750

Address findings surfaced by `pre-push-review` after the round 8 sweep:

- Add deck verifier symmetry tests (404, transient 5xx, unexpected
  exception, non-numeric metadata) so deck has the same shape as the
  notes/news/files verifiers. Also add unexpected-exception tests for
  the news and file verifiers, which had `except Exception` branches
  no test was reaching. Keeps the registry-style verifier coverage
  uniform.
- Modernize sibling field types in `VectorSyncState`, `AppContext`,
  and `OAuthAppContext` from `Optional[X]` to `X | None`, matching the
  `eviction_task_group: TaskGroup | None` field added in the round 8
  diff (resolves the inconsistency flagged by A6). The lone remaining
  `Optional` import is dropped.
- Reverse cross-reference direction in the verifier docstrings: the
  later-defined `_verify_deck_cards` and `_verify_news_items` now
  point at `_verify_notes` as the canonical hoisted-cast pattern,
  rather than `_verify_notes` forward-referring to verifiers defined
  below it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/app.py

@@ -9,7 +9,7 @@ import traceback
 from collections.abc import AsyncIterator
 from contextlib import AsyncExitStack, asynccontextmanager
 from dataclasses import dataclass
-from typing import Optional, cast
+from typing import cast
 from urllib.parse import urlparse
 
 import anyio
@@ -316,10 +316,10 @@ class VectorSyncState:
     and FastMCP session lifespans (where MCP tools need access to the streams).
     """
 
-    document_send_stream: Optional[MemoryObjectSendStream] = None
-    document_receive_stream: Optional[MemoryObjectReceiveStream] = None
-    shutdown_event: Optional[anyio.Event] = None
-    scanner_wake_event: Optional[anyio.Event] = None
+    document_send_stream: MemoryObjectSendStream | None = None
+    document_receive_stream: MemoryObjectReceiveStream | None = None
+    shutdown_event: anyio.Event | None = None
+    scanner_wake_event: anyio.Event | None = None
     # Long-lived task group used for fire-and-forget background work spawned
     # from the request path (e.g. ADR-019 verify-on-read eviction). Set by the
     # starlette lifespan after entering its task group; cleared on shutdown.
@@ -335,11 +335,11 @@ class AppContext:
     """Application context for BasicAuth mode."""
 
     client: NextcloudClient
-    storage: Optional["RefreshTokenStorage"] = None
-    document_send_stream: Optional[MemoryObjectSendStream] = None
-    document_receive_stream: Optional[MemoryObjectReceiveStream] = None
-    shutdown_event: Optional[anyio.Event] = None
-    scanner_wake_event: Optional[anyio.Event] = None
+    storage: "RefreshTokenStorage | None" = None
+    document_send_stream: MemoryObjectSendStream | None = None
+    document_receive_stream: MemoryObjectReceiveStream | None = None
+    shutdown_event: anyio.Event | None = None
+    scanner_wake_event: anyio.Event | None = None
 
     @property
     def eviction_task_group(self) -> TaskGroup | None:
@@ -357,16 +357,14 @@ class OAuthAppContext:
 
     nextcloud_host: str
     token_verifier: object  # UnifiedTokenVerifier (ADR-005 compliant)
-    refresh_token_storage: Optional["RefreshTokenStorage"] = None
-    oauth_client: Optional[object] = None
+    refresh_token_storage: "RefreshTokenStorage | None" = None
+    oauth_client: object | None = None
     oauth_provider: str = "nextcloud"  # "nextcloud" or "keycloak"
-    server_client_id: Optional[str] = (
-        None  # MCP server's OAuth client ID (static or DCR)
-    )
-    document_send_stream: Optional[MemoryObjectSendStream] = None
-    document_receive_stream: Optional[MemoryObjectReceiveStream] = None
-    shutdown_event: Optional[anyio.Event] = None
-    scanner_wake_event: Optional[anyio.Event] = None
+    server_client_id: str | None = None  # MCP server's OAuth client ID (static or DCR)
+    document_send_stream: MemoryObjectSendStream | None = None
+    document_receive_stream: MemoryObjectReceiveStream | None = None
+    shutdown_event: anyio.Event | None = None
+    scanner_wake_event: anyio.Event | None = None
 
     @property
     def eviction_task_group(self) -> TaskGroup | None: