fix: add tts_failed and render_failed to MongoDB schema validator

MongoDB was rejecting status updates to 'tts_failed' and 'render_failed'
because these values weren't in the schema validator's enum, even though
they were defined in the Python JobStatus model.

This caused TTS failures to leave jobs stuck in 'tts_generating' status
with no error feedback to users - the WriteError from MongoDB prevented
the status and error fields from being updated.

The migration adds both failed statuses to the jobs collection validator.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/migrations/scripts/migration_2026-01-05-000000_add_failed_statuses.py

@@ -0,0 +1,114 @@
+"""Add tts_failed and render_failed statuses to jobs collection validator.
+
+These statuses were defined in the Python model but missing from the MongoDB
+schema validation, causing WriteError when setting job status to failed states.
+"""
+
+from app.migrations.migrator import Migration
+
+
+class Migration(Migration):
+    """Update MongoDB schema validator to support tts_failed and render_failed statuses."""
+
+    def __init__(self):
+        super().__init__()
+        self.version = "2026-01-05-000000"
+        self.description = "Add tts_failed and render_failed statuses to jobs collection"
+
+    async def up(self) -> None:
+        """Update the jobs collection validator to include failed statuses."""
+
+        # Define updated schema validator with failed statuses
+        validator = {
+            "$jsonSchema": {
+                "bsonType": "object",
+                "required": ["_id", "title", "status", "client_id", "created_at", "updated_at"],
+                "properties": {
+                    "_id": {"bsonType": "string"},
+                    "title": {"bsonType": "string"},
+                    "status": {
+                        "enum": [
+                            "created",
+                            "ingesting",
+                            "ai_processing",
+                            "pending_qc",
+                            "approved_english",
+                            "approved_source",
+                            "rejected",
+                            "qc_feedback",
+                            "translating",
+                            "tts_generating",
+                            "tts_failed",        # NEW: TTS synthesis failed after retries
+                            "rendering_video",
+                            "render_failed",     # NEW: Accessible video rendering failed
+                            "pending_final_review",
+                            "completed"
+                        ]
+                    },
+                    "client_id": {"bsonType": "string"},
+                    "created_at": {"bsonType": "date"},
+                    "updated_at": {"bsonType": "date"}
+                }
+            }
+        }
+
+        # Update the collection validator
+        try:
+            await self.db.command({
+                "collMod": "jobs",
+                "validator": validator,
+                "validationLevel": "moderate",
+                "validationAction": "error"
+            })
+            print(f"  Updated jobs collection validator")
+        except Exception as e:
+            print(f"  Could not update validator: {e}")
+            raise
+
+        print(f"  Applied migration {self.version}: {self.description}")
+
+    async def down(self) -> None:
+        """Revert to previous validator (without failed statuses)."""
+
+        # Define old schema validator
+        validator = {
+            "$jsonSchema": {
+                "bsonType": "object",
+                "required": ["_id", "title", "status", "client_id", "created_at", "updated_at"],
+                "properties": {
+                    "_id": {"bsonType": "string"},
+                    "title": {"bsonType": "string"},
+                    "status": {
+                        "enum": [
+                            "created",
+                            "ingesting",
+                            "ai_processing",
+                            "pending_qc",
+                            "approved_english",
+                            "approved_source",
+                            "rejected",
+                            "qc_feedback",
+                            "translating",
+                            "tts_generating",
+                            "rendering_video",
+                            "pending_final_review",
+                            "completed"
+                        ]
+                    },
+                    "client_id": {"bsonType": "string"},
+                    "created_at": {"bsonType": "date"},
+                    "updated_at": {"bsonType": "date"}
+                }
+            }
+        }
+
+        # Update the collection validator
+        await self.db.command({
+            "collMod": "jobs",
+            "validator": validator,
+            "validationLevel": "moderate",
+            "validationAction": "error"
+        })
+
+        print(f"  Rolled back migration {self.version}: {self.description}")
+        print(f"  WARNING: Jobs with tts_failed or render_failed status will fail validation!")