fix: address PR #632 review comments

- Update stale httpx reference to niquests in calendar.py type comment
- Replace inline inspect.isawaitable with _maybe_await helper in tests
- Fix incorrect port number in docker-compose unstructured comment
- Remove commented-out smithery service block (dead code)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/client/calendar.py

@@ -51,7 +51,7 @@ class CalendarClient:
             url=f"{base_url}/remote.php/dav/",
             username=username,
             auth=auth,
-            ssl_verify_cert=get_nextcloud_ssl_verify(),  # type: ignore[arg-type]  # caldav types say bool|str but passes through to httpx which accepts SSLContext
+            ssl_verify_cert=get_nextcloud_ssl_verify(),  # type: ignore[arg-type]  # caldav types say bool|str but passes through to niquests which accepts SSLContext
         )
         self._calendar_home_url = f"{base_url}/remote.php/dav/calendars/{username}/"