Fix: require context manager for TikaDocumentParser; clean up client lifecycle

- consumer.py: call __enter__ for new-style parsers so _tika_client and
  _gotenberg_client are set before parse() is invoked
- views.py: use `with parser` (via nullcontext for old-style parsers) in
  get_metadata so extract_metadata always runs inside a context manager
- tika.py: GotenbergClient added to ExitStack alongside TikaClient;
  inline client creation removed from extract_metadata and _convert_to_pdf;
  __exit__ uses ExitStack.close() instead of __exit__ pass-through

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/documents/consumer.py

@@ -449,6 +449,12 @@ class ConsumerPlugin(
             progress_callback=progress_callback,
         )
 
+        # New-style parsers use __enter__/__exit__ for resource management.
+        # _parser_cleanup (below) handles __exit__; call __enter__ here.
+        # TODO(stumpylog): Remove me in the future
+        if isinstance(document_parser, (TextDocumentParser, TikaDocumentParser)):
+            document_parser.__enter__()
+
         self.log.debug(f"Parser: {type(document_parser).__name__}")
 
         # Parse the document. This may take some time.

src/documents/views.py

@@ -7,6 +7,7 @@ import tempfile
 import zipfile
 from collections import defaultdict
 from collections import deque
+from contextlib import nullcontext
 from datetime import datetime
 from pathlib import Path
 from time import mktime
@@ -225,6 +226,7 @@ from paperless.celery import app as celery_app
 from paperless.config import AIConfig
 from paperless.config import GeneralConfig
 from paperless.models import ApplicationConfiguration
+from paperless.parsers import ParserProtocol
 from paperless.serialisers import GroupSerializer
 from paperless.serialisers import UserSerializer
 from paperless.views import StandardPagination
@@ -1084,9 +1086,11 @@ class DocumentViewSet(
         parser_class = get_parser_class_for_mime_type(mime_type)
         if parser_class:
             parser = parser_class(progress_callback=None, logging_group=None)
+            cm = parser if isinstance(parser, ParserProtocol) else nullcontext(parser)
 
             try:
-                return parser.extract_metadata(file, mime_type)
+                with cm:
+                    return parser.extract_metadata(file, mime_type)
             except Exception:  # pragma: no cover
                 logger.exception(f"Issue getting metadata for {file}")
                 # TODO: cover GPG errors, remove later.