fix: stop S7632 flagging NOSONAR mentioned in prose comments

SonarCloud's python:S7632 parses the literal ``# NOSONAR`` token wherever it
appears — including inside explanatory comments that *quote* the directive —
and treats the following text as a malformed suppression. The actual bare
``# NOSONAR`` suppression lines are fine; the flagged lines were the prose
comments describing them. Reword those comments to drop the inner ``#`` so the
analyzer no longer sees a directive.

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

nextcloud_mcp_server/vector/queue/postgres.py

@@ -45,7 +45,7 @@ class PostgresTaskProducer:
     ) -> None:  # pragma: no cover
         return None
 
-    # Bare ``# NOSONAR`` silences ``python:S7503`` (async method without await):
+    # The bare suppression marker silences S7503 (async method without await):
     # ``async def`` is required by the TaskProducer protocol; this stub is a
     # no-op until the Postgres transport lands.
     async def aclose(self) -> None:  # NOSONAR  # pragma: no cover