게시물 export 진행도 표시 추가 v1.5.21

db/migrations/041_post_export_progress.sql

@@ -0,0 +1,15 @@
+ALTER TABLE post_export_jobs
+  ADD COLUMN IF NOT EXISTS processed_count INTEGER NOT NULL DEFAULT 0;
+
+ALTER TABLE post_export_jobs
+  ADD COLUMN IF NOT EXISTS current_part_index INTEGER;
+
+ALTER TABLE post_export_jobs
+  ADD COLUMN IF NOT EXISTS progress_message TEXT NOT NULL DEFAULT '';
+
+ALTER TABLE post_export_jobs
+  ADD COLUMN IF NOT EXISTS started_at TIMESTAMPTZ;
+
+ALTER TABLE post_export_jobs
+  ADD CONSTRAINT post_export_jobs_processed_count_check
+  CHECK (processed_count >= 0);