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/documents/permissions.py

@@ -359,6 +359,13 @@ def get_objects_for_user_owner_aware(
     """
     Returns objects the user owns, are unowned, or has explicit perms.
     When include_deleted is True, soft-deleted items are also included.
+
+    Legacy slow path (guardian-backed, O(n) style permission resolution).
+    Most queryset-filtering call sites have migrated onto
+    ``PermittedObjectsFilter``/``permitted_object_ids()``, but this function
+    is kept because production callers still remain. Several callers remain
+    across ``documents/``, ``paperless_mail/``, and ``paperless_ai/`` --
+    grep for this function name before removing it.
     """
     manager = (
         Model.global_objects
@@ -378,6 +385,15 @@ def get_objects_for_user_owner_aware(
 
 
 def has_perms_owner_aware(user, perms, obj):
+    """
+    Legacy slow path (guardian-backed) single-object permission check.
+
+    The queryset-filtering side of this migrated onto
+    ``PermittedObjectsFilter``/``permitted_object_ids()``, but this
+    single-object check still has many production callers. Several callers
+    remain across ``documents/``, ``paperless_mail/``, and ``paperless_ai/``
+    -- grep for this function name before removing it.
+    """
     checker = ObjectPermissionChecker(user)
     return obj.owner is None or obj.owner == user or checker.has_perm(perms, obj)