Add @extend_schema decorators to moderation ViewSet actions

- Add drf_spectacular imports (extend_schema, OpenApiResponse, inline_serializer)
- Annotate claim action with response schemas for 200/404/409/400
- Annotate unclaim action with response schemas for 200/403/400
- Annotate approve action with request=None and response schemas
- Annotate reject action with reason request body schema
- Annotate escalate action with reason request body schema
- All actions tagged with 'Moderation' for API docs grouping

backend/apps/moderation/tests/test_comprehensive.py

@@ -3,7 +3,7 @@ Comprehensive tests for the moderation app.
 
 This module contains tests for:
 - EditSubmission state machine transitions
-- PhotoSubmission state machine transitions
+- EditSubmission with submission_type="PHOTO" (photo submissions)
 - ModerationReport state machine transitions
 - ModerationQueue state machine transitions
 - BulkOperation state machine transitions
@@ -39,7 +39,6 @@ from ..models import (
     ModerationAction,
     ModerationQueue,
     ModerationReport,
-    PhotoSubmission,
 )
 
 User = get_user_model()
@@ -1132,14 +1131,17 @@ class ModerationActionTests(TestCase):
 
 
 # ============================================================================
-# PhotoSubmission FSM Transition Tests
+# EditSubmission PHOTO Type FSM Transition Tests
 # ============================================================================
 
 
-class PhotoSubmissionTransitionTests(TestCase):
-    """Comprehensive tests for PhotoSubmission FSM transitions.
+class PhotoEditSubmissionTransitionTests(TestCase):
+    """Comprehensive tests for EditSubmission with submission_type='PHOTO' FSM transitions.
     
     Note: All approve/reject/escalate transitions require CLAIMED state first.
+    
+    These tests validate that photo submissions (using the unified EditSubmission model)
+    have correct FSM behavior.
     """
 
     def setUp(self):
@@ -1169,13 +1171,15 @@ class PhotoSubmissionTransitionTests(TestCase):
         )
 
     def _create_submission(self, status="PENDING"):
-        """Helper to create a PhotoSubmission with proper CloudflareImage."""
-        submission = PhotoSubmission.objects.create(
+        """Helper to create an EditSubmission with submission_type='PHOTO' and proper CloudflareImage."""
+        submission = EditSubmission.objects.create(
             user=self.user,
             content_type=self.content_type,
             object_id=self.operator.id,
+            submission_type="PHOTO",  # Unified model
             photo=self.mock_image,
             caption="Test Photo",
+            changes={},  # Photos use empty changes
             status="PENDING",  # Always create as PENDING first
         )