fix: implement deletion grace period and vector sync status tool

This commit addresses issues with vector database synchronization that
were causing test failures:

1. **Deletion Grace Period** (scanner.py)
   - Fixed premature deletion of documents due to pagination cursor
     inconsistencies in Notes API
   - Implemented 2-scan verification with 1.5x scan interval grace period
     (15 seconds default)
   - Documents must be missing for 2 consecutive scans before deletion
   - Documents that reappear are removed from deletion tracking
   - Prevents false deletions during concurrent note creation/indexing

2. **Vector Sync Status Tool** (server/notes.py, models/notes.py)
   - Added nc_notes_get_vector_sync_status MCP tool
   - Returns indexed_count, pending_count, status, and enabled fields
   - Enables tests and clients to wait for vector sync completion
   - Uses lifespan context to access document queue and Qdrant client

3. **Test Improvements** (test_sampling.py, conftest.py)
   - Added temporary_note_factory fixture for creating multiple test notes
   - Updated all sampling tests to wait for vector sync completion
   - Adjusted score_threshold to 0.0 for SimpleEmbeddingProvider
     (feature hashing produces low-quality embeddings)
   - Fixed CallToolResult extraction (removed ["result"] key access)
   - Removed invalid @pytest.mark.asyncio markers (anyio mode)

All integration tests now pass successfully.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/conftest.py

@@ -550,6 +550,43 @@ async def temporary_note(nc_client: NextcloudClient):
                 logger.error(f"Unexpected error deleting temporary note {note_id}: {e}")
 
 
+@pytest.fixture
+async def temporary_note_factory(nc_client: NextcloudClient):
+    """
+    Factory fixture to create multiple temporary notes with custom parameters.
+    Returns a callable that creates notes and tracks them for automatic cleanup.
+    """
+    created_notes = []
+
+    async def _create_note(title: str, content: str, category: str = ""):
+        """Create a temporary note with custom title, content, and category."""
+        logger.info(f"Creating temporary note via factory: {title}")
+        note_data = await nc_client.notes.create_note(
+            title=title, content=content, category=category
+        )
+        note_id = note_data.get("id")
+        if note_id:
+            created_notes.append(note_id)
+            logger.info(f"Factory created note ID: {note_id}")
+        return note_data
+
+    yield _create_note
+
+    # Cleanup all created notes
+    for note_id in created_notes:
+        logger.info(f"Cleaning up factory-created note ID: {note_id}")
+        try:
+            await nc_client.notes.delete_note(note_id=note_id)
+            logger.info(f"Successfully deleted factory note ID: {note_id}")
+        except HTTPStatusError as e:
+            if e.response.status_code != 404:
+                logger.error(f"HTTP error deleting factory note {note_id}: {e}")
+            else:
+                logger.warning(f"Factory note {note_id} already deleted (404).")
+        except Exception as e:
+            logger.error(f"Unexpected error deleting factory note {note_id}: {e}")
+
+
 @pytest.fixture
 async def temporary_note_with_attachment(
     nc_client: NextcloudClient, temporary_note: dict