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/tests/test_permission_filtering_security.py

@@ -446,6 +446,33 @@ class TestTrashRestorePermissionBoundary:
         assert response.status_code == HTTPStatus.OK
 
 
+@pytest.mark.django_db
+class TestTrashViewExcludesExplicitlyGrantedDocuments:
+    """
+    Regression test pinning TrashView's use of
+    ``_TrashPermittedObjectsFilter`` (``include_granted = False``). If that
+    flag were ever flipped to the default ``True``, or the subclass removed
+    in favor of the base ``PermittedObjectsFilter``, a trashed document
+    would leak into ``/api/trash/`` results for any user holding an
+    explicit guardian grant on it, even though they are neither the owner
+    nor a superuser.
+    """
+
+    def test_explicit_grant_does_not_leak_trashed_document(self, rest_api_client):
+        owner = User.objects.create_user(username="trash_owner")
+        grantee = User.objects.create_user(username="trash_grantee")
+        doc = DocumentFactory(owner=owner)
+        doc.delete()  # soft delete
+        assign_perm("view_document", grantee, doc)
+
+        rest_api_client.force_authenticate(user=grantee)
+        response = rest_api_client.get("/api/trash/")
+
+        assert response.status_code == HTTPStatus.OK
+        result_ids = {result["id"] for result in response.data["results"]}
+        assert doc.pk not in result_ids
+
+
 @pytest.mark.django_db
 @pytest.mark.parametrize(
     ("model", "factory", "perm"),

src/documents/tests/test_permitted_objects_filter.py

@@ -0,0 +1,70 @@
+import pytest
+from django.contrib.auth.models import User
+from guardian.shortcuts import assign_perm
+from rest_framework.test import APIRequestFactory
+
+from documents.filters import PermittedObjectsFilter
+from documents.models import Tag
+from documents.tests.factories import TagFactory
+
+
+class _DummyView:
+    queryset = Tag.objects.all()
+
+
+@pytest.mark.django_db
+class TestPermittedObjectsFilter:
+    def test_superuser_bypasses_filtering_entirely(self):
+        superuser = User.objects.create_superuser(username="root")
+        owner = User.objects.create_user(username="owner")
+        TagFactory(owner=owner)
+        request = APIRequestFactory().get("/")
+        request.user = superuser
+
+        result = PermittedObjectsFilter().filter_queryset(
+            request,
+            Tag.objects.all(),
+            _DummyView(),
+        )
+        assert result.count() == Tag.objects.count()
+
+    def test_non_superuser_sees_only_owned_unowned_and_granted(self):
+        owner = User.objects.create_user(username="owner")
+        grantee = User.objects.create_user(username="grantee")
+        owned = TagFactory(owner=grantee)
+        unowned = TagFactory(owner=None)
+        granted = TagFactory(owner=owner)
+        hidden = TagFactory(owner=owner)
+        assign_perm("view_tag", grantee, granted)
+        request = APIRequestFactory().get("/")
+        request.user = grantee
+
+        result = PermittedObjectsFilter().filter_queryset(
+            request,
+            Tag.objects.all(),
+            _DummyView(),
+        )
+        visible_ids = set(result.values_list("id", flat=True))
+        assert visible_ids == {owned.pk, unowned.pk, granted.pk}
+        assert hidden.pk not in visible_ids
+
+    def test_include_granted_false_excludes_explicitly_shared_objects(self):
+        owner = User.objects.create_user(username="owner2")
+        grantee = User.objects.create_user(username="grantee2")
+        owned = TagFactory(owner=grantee)
+        granted = TagFactory(owner=owner)
+        assign_perm("view_tag", grantee, granted)
+        request = APIRequestFactory().get("/")
+        request.user = grantee
+
+        class _OwnerOnlyFilter(PermittedObjectsFilter):
+            include_granted = False
+
+        result = _OwnerOnlyFilter().filter_queryset(
+            request,
+            Tag.objects.all(),
+            _DummyView(),
+        )
+        visible_ids = set(result.values_list("id", flat=True))
+        assert visible_ids == {owned.pk}
+        assert granted.pk not in visible_ids