fix(migrations): correct listCollections cursor parsing, add processing_failed+cancelled to status enum

Previous migrations used async-for on a dict (Atlas returns firstBatch, not
async cursor) — silently failed. New migration reads firstBatch correctly and
sets the complete status list.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/migrations/scripts/migration_2026-04-30-000002_fix_status_enum.py

@@ -0,0 +1,47 @@
+"""Replace status enum in $jsonSchema validator with the full current list."""
+from app.migrations.migrator import Migration
+
+ALL_STATUSES = [
+    "created", "ingesting", "ai_processing",
+    "pending_qc", "approved_english", "approved_source",
+    "rejected", "qc_feedback",
+    "translating", "tts_generating", "tts_failed",
+    "rendering_video", "render_failed", "rendering_qc",
+    "pending_final_review", "completed",
+    "processing_failed", "cancelled",
+]
+
+
+class Migration(Migration):
+    version = "2026-04-30-000002"
+    description = "Fix status enum in jobs $jsonSchema validator (add processing_failed + cancelled)"
+
+    async def up(self) -> None:
+        db = self.db
+
+        result = await db.command("listCollections", filter={"name": "jobs"})
+        batch = result.get("cursor", {}).get("firstBatch", [])
+        if not batch:
+            return
+
+        existing_validator = batch[0].get("options", {}).get("validator")
+        if not existing_validator:
+            return
+
+        schema = existing_validator.get("$jsonSchema", {})
+        status_prop = schema.get("properties", {}).get("status")
+        if not status_prop:
+            return
+
+        status_prop["enum"] = ALL_STATUSES
+
+        await db.command(
+            "collMod",
+            "jobs",
+            validator=existing_validator,
+            validationLevel="moderate",
+            validationAction="error",
+        )
+
+    async def down(self) -> None:
+        pass