fix(jobs): add missing migration for job_type_key choices

Job.job_type_key builds its choices from VALID_JOB_TYPES, so registry changes
(post_processing and data_export job types added since the last migration)
alter the field definition. The migration is state-only — no database schema
change — but Django requires it, and the new makemigrations --check CI step
fails without it. Documented the gotcha in the agent instructions.

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

Author: mihow

.agents/AGENTS.md

@@ -110,6 +110,7 @@ Silent-bug classes that reviewers have caught repeatedly. None of these are visi
 - **Raise, don't return sentinels.** Failure paths raise exceptions (or surface DRF 4xx via serializer validation) — never return an empty/None "success" response on error.
 - **No `assert` in production code.** Assertions are stripped under `python -O`. Raise explicit exceptions.
 - **Model change ⇒ migration in the same PR.** Run `python manage.py makemigrations --check --dry-run` before pushing (CI enforces this). A missing migration discovered mid-branch that belongs to main gets its own PR branched from main.
+- **Changing `VALID_JOB_TYPES` requires a migration.** `Job.job_type_key` builds its `choices` from the registry, so adding/renaming a job type changes the field definition. The migration is state-only (no schema change), but Django still requires it, and it is easy to miss because nothing in the database schema changes.
 
 ## Development Commands
 

ami/jobs/migrations/0023_alter_job_job_type_key.py

@@ -0,0 +1,29 @@
+# Generated by Django 4.2.10 on 2026-06-09 18:21
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("jobs", "0022_alter_job_logs_help_text"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="job",
+            name="job_type_key",
+            field=models.CharField(
+                choices=[
+                    ("ml", "ML pipeline"),
+                    ("populate_captures_collection", "Populate capture set"),
+                    ("data_storage_sync", "Data storage sync"),
+                    ("unknown", "Unknown"),
+                    ("data_export", "Data Export"),
+                    ("post_processing", "Post Processing"),
+                ],
+                default="unknown",
+                max_length=255,
+                verbose_name="Job Type",
+            ),
+        ),
+    ]