fix(review): close doc via try/finally; don't count parse failures as indexed

Address PR #852 review:

- pymupdf.py: the metadata `doc` was only closed on the PdfParseFailed and
  success paths, so a failure in `_extract_metadata`/`mkdir`/`get_settings`
  leaked it. `doc` is only needed for metadata + page_count (the heavy parse
  works from `content` bytes in the worker), so open it, read metadata, and
  close it immediately under try/finally; drop the two later doc.close() calls.

- processor.py: a permanent parse failure early-returned from `_index_document`,
  after which `process_document` still recorded record_qdrant_operation("upsert",
  "success") + record_vector_sync_processing(success) -- counting an OOM/timeout
  bomb as astrolabe_documents_indexed_total{status="success"}. `_index_document`
  now returns False on that path and the caller skips the success metrics (the
  failure is already recorded via document_parse_failed_total + the registry's
  document_parse_total{error}).

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

nextcloud_mcp_server/vector/processor.py

@@ -237,7 +237,15 @@ async def process_document(
 
             for attempt in range(max_retries):
                 try:
-                    await _index_document(doc_task, nc_client, qdrant_client)
+                    indexed = await _index_document(doc_task, nc_client, qdrant_client)
+
+                    # A permanent parse failure returns False: it was already
+                    # recorded (document_parse_failed_total + the registry's
+                    # document_parse_total{error}) and the placeholder marked
+                    # "failed". It is not an indexing event and not retryable, so
+                    # don't count it as a successful upsert/indexed document.
+                    if indexed is False:
+                        return
 
                     # Record successful processing metrics
                     duration = time.time() - start_time
@@ -534,8 +542,8 @@ async def _index_document(
                 # on a pathological PDF) returns success=False rather than
                 # raising -- there is nothing to index and retrying would just
                 # fail again. Mark the placeholder "failed" so the scanner stops
-                # re-queuing it (until the file changes) and return without
-                # indexing empty content.
+                # re-queuing it (until the file changes) and return False so the
+                # caller skips the success metrics (it was not indexed).
                 if not result.success:
                     reason = result.metadata.get("parse_failed_reason", "error")
                     record_document_parse_failed(reason)
@@ -561,7 +569,7 @@ async def _index_document(
                             doc_task.doc_id,
                             exc_info=True,
                         )
-                    return
+                    return False
 
                 content = result.text
                 file_metadata = result.metadata