fix: resolve startup NameError in vector-sync metrics task

The Starlette lifespan started `vector_sync_metrics_task` with undefined
names `task_producer` and `receive_stream`. Those locals only exist inside
the `_wire_vector_sync_state` helper; in the lifespan the transport is bound
as `ingest_transport`. The undefined reference raised `NameError`, which
aborted the background-sync task group and crashed startup in every
deployment mode ("Application startup failed. Exiting.").

Introduced by fbe70ecd ("feat: backend-agnostic vector-sync gauges").

Pass `ingest_transport.producer` / `ingest_transport.receive_stream` at both
call sites (single-user app.py:1791, OAuth/login-flow app.py:2012).

Also fix 10 pre-existing `ty` possibly-missing-attribute diagnostics: the
deck indexing code in scanner.py, processor.py and search/context.py reads
full-DeckCard-only fields (description, type, owner, etag, lastModified) off
`stack.cards`, typed `list[DeckCard | DeckCardSummary]`. Freshly-fetched
stacks from `get_stacks()` always hold full DeckCards (the summary
projection only happens in the tool layer), so narrow with
`cast(list[DeckCard], ...)` — matching the existing pattern in
server/deck.py.

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

nextcloud_mcp_server/vector/processor.py

@@ -18,6 +18,7 @@ from nextcloud_mcp_server.client import NextcloudClient
 from nextcloud_mcp_server.config import get_settings
 from nextcloud_mcp_server.document_processors import get_registry
 from nextcloud_mcp_server.embedding import get_bm25_service, get_embedding_service
+from nextcloud_mcp_server.models.deck import DeckCard
 from nextcloud_mcp_server.observability.metrics import (
     record_document_chunks,
     record_embedding,
@@ -421,7 +422,10 @@ async def _index_document(
                         if card_found:
                             break
                         if s.cards:
-                            for c in s.cards:
+                            # get_stacks() always yields full DeckCard objects;
+                            # the DeckCardSummary projection only happens in the
+                            # tool layer, never on freshly-fetched stacks.
+                            for c in cast(list[DeckCard], s.cards):
                                 if c.id == int(doc_task.doc_id):
                                     card = c
                                     board = b