chore(migrations): add 0013 rebuild checkpoint table (was untracked)

Made-with: Cursor

backend/pipeline/migrations/0013_rebuild_pipelinejobcheckpoint.py

@@ -0,0 +1,34 @@
+# 0012 曾标记为已应用，但部分环境上 checkpoint 表仍为旧版 schema（stage/page_done 等）。
+# 与当前 PipelineJobCheckpoint（phase/payload/hint_zh）对齐：删表后按 0012 预期 DDL 重建。
+
+from django.db import migrations
+
+
+_REBUILD_SQL = """
+DROP TABLE IF EXISTS pipeline_pipelinejobcheckpoint;
+CREATE TABLE "pipeline_pipelinejobcheckpoint" (
+    "id" integer NOT NULL PRIMARY KEY AUTOINCREMENT,
+    "phase" varchar(32) NOT NULL,
+    "payload" text NOT NULL CHECK ((JSON_VALID("payload") OR "payload" IS NULL)),
+    "hint_zh" text NOT NULL,
+    "updated_at" datetime NOT NULL,
+    "job_id" bigint NOT NULL UNIQUE REFERENCES "pipeline_pipelinejob" ("id") DEFERRABLE INITIALLY DEFERRED
+);
+CREATE INDEX "pipeline_pipelinejobcheckpoint_phase_12e50a62" ON "pipeline_pipelinejobcheckpoint" ("phase");
+"""
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("pipeline", "0012_job_pause_checkpoint"),
+    ]
+
+    operations = [
+        migrations.SeparateDatabaseAndState(
+            state_operations=[],
+            database_operations=[
+                migrations.RunSQL(_REBUILD_SQL, reverse_sql=migrations.RunSQL.noop),
+            ],
+        ),
+    ]