fix: address PR #836 review — forward task_producer to MCP contexts + cleanups

🔴 nc_get_vector_sync_status reported pending=0 for INGEST_QUEUE=postgres: the
AppContext/OAuthAppContext per-session yields snapshotted the stream fields but
never forwarded task_producer, so lifespan_ctx.task_producer was always None.
Convert task_producer to a @property that reads _vector_sync_state live (like
eviction_task_group), removing the snapshot field so the yields can't drop it.
Add a regression test pinning the contract on both contexts.

🟡 Remove the unused _RECLAIM_TASK_NAME constant.
🟡 get_procrastinate_conninfo: warn + document that DATABASE_URL query params
   (application_name, connect_timeout, …) are dropped.
🟡 worker: open the procrastinate App once — apply_ingest_queue_schema gains
   manage_connection=False so the worker reuses its own open connector instead
   of a redundant open/close before run_worker_async.

🟢 Clarify the apply-schema broad-except comment (non-race errors re-raise) and
   document the deliberate Any typing in ingest_status.get_ingest_pending.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/vector/ingest_status.py

@@ -36,6 +36,12 @@ async def get_ingest_pending(
 ) -> IngestPending:
     """Compute outstanding ingest work for the configured queue backend.
 
+    ``task_producer`` and ``document_receive_stream`` are intentionally typed
+    ``Any``: they're duck-typed across backends. Only ``ProcrastinateTaskProducer``
+    exposes ``job_counts`` (the ``TaskProducer`` protocol doesn't), and the memory
+    backend reads the anyio stream's ``statistics()`` — so no single concrete type
+    or Protocol fits both branches, and we probe with ``hasattr`` instead.
+
     Never raises — a status surface must stay available even if the queue is
     unreachable; failures degrade to ``pending=0``.
     """