Performance: unify permission-filtering backends, fixes Correspondent/Tag list slowness (#13601)

* feat: add unified PermittedObjectsFilter backed by permitted_object_ids

* refactor: migrate all ViewSets to unified PermittedObjectsFilter

Replace the deprecated ObjectOwnedOrGrantedPermissionsFilter,
DocumentPermissionsFilter, and ObjectOwnedPermissionsFilter aliases
with PermittedObjectsFilter directly across documents/views.py (8
sites, including TrashView's include_granted=False subclass) and
paperless_mail/views.py (3 sites), then delete the now-unreferenced
alias classes from documents/filters.py.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UFyrt7FWbRRdTUAcdqBcsc

* docs: document legacy status of get_objects_for_user_owner_aware/has_perms_owner_aware

Stage 4's PermittedObjectsFilter/permitted_object_ids() covers the
queryset-filtering use case, but both functions still have production
callers outside this plan's scope (documents/views.py,
documents/serialisers.py, documents/signals/handlers.py,
paperless_ai/matching.py, paperless_ai/ai_classifier.py). Per Task 20
Step 2, they are kept in place rather than partially deleted, with
docstrings updated to note their legacy status and remaining callers.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UFyrt7FWbRRdTUAcdqBcsc

* Fix: address final review findings for permission-filter unification

- Add a permanent regression test pinning TrashView's include_granted=False
  wiring: an explicit view_document grant on a trashed document must not
  leak it into /api/trash/ for a non-owner, non-superuser requester.
- Drop the now-dead direct dependency djangorestframework-guardian; the
  last rest_framework_guardian import was removed by this branch's
  migration onto PermittedObjectsFilter. django-guardian is untouched.
- Replace the hand-maintained, already-stale caller lists in
  get_objects_for_user_owner_aware/has_perms_owner_aware docstrings with a
  pointer to grep for remaining callers instead.
- In PermittedObjectsFilter.filter_queryset, compute `model` only on the
  include_granted=True path that actually uses it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UFyrt7FWbRRdTUAcdqBcsc

* perf: check bulk-edit-objects apply_to_all permissions via DB-side exclude/exists

Materialized the full permitted_object_ids() set into a Python set() just
to check membership for the request's objs queryset -- the same pattern
already fixed at four other sites for Document. This one is used by
apply_to_all, where objs can be an unbounded filtered selection (e.g. all
tags matching a filter) rather than a small request-supplied ID list,
making the wasted materialization worse here than at the sites already
fixed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* Cleans up the comment about why this is still here for now

---------

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

src/paperless_mail/views.py

@@ -23,7 +23,7 @@ from rest_framework.response import Response
 from rest_framework.viewsets import ModelViewSet
 from rest_framework.viewsets import ReadOnlyModelViewSet
 
-from documents.filters import ObjectOwnedOrGrantedPermissionsFilter
+from documents.filters import PermittedObjectsFilter
 from documents.models import PaperlessTask
 from documents.permissions import PaperlessObjectPermissions
 from documents.permissions import has_perms_owner_aware
@@ -75,7 +75,7 @@ class MailAccountViewSet(PassUserMixin, ModelViewSet[MailAccount]):
     serializer_class = MailAccountSerializer
     pagination_class = StandardPagination
     permission_classes = (IsAuthenticated, PaperlessObjectPermissions)
-    filter_backends = (ObjectOwnedOrGrantedPermissionsFilter,)
+    filter_backends = (PermittedObjectsFilter,)
 
     def get_permissions(self):
         if self.action == "test":
@@ -197,7 +197,7 @@ class ProcessedMailViewSet(PassUserMixin, ReadOnlyModelViewSet[ProcessedMail]):
     filter_backends = (
         DjangoFilterBackend,
         OrderingFilter,
-        ObjectOwnedOrGrantedPermissionsFilter,
+        PermittedObjectsFilter,
     )
     filterset_class = ProcessedMailFilterSet
 
@@ -225,7 +225,7 @@ class MailRuleViewSet(PassUserMixin, ModelViewSet[MailRule]):
     serializer_class = MailRuleSerializer
     pagination_class = StandardPagination
     permission_classes = (IsAuthenticated, PaperlessObjectPermissions)
-    filter_backends = (ObjectOwnedOrGrantedPermissionsFilter,)
+    filter_backends = (PermittedObjectsFilter,)
 
 
 @extend_schema_view(