feat: GTSIT 사이트 구축

database/migrate-20260805-inquiry-pin.sql

@@ -0,0 +1,8 @@
+ALTER TABLE inquiries
+  ADD COLUMN IF NOT EXISTS closed_at DATETIME NULL AFTER replied_at,
+  ADD COLUMN IF NOT EXISTS lookup_failed_attempts TINYINT UNSIGNED NOT NULL DEFAULT 0 AFTER closed_at,
+  ADD COLUMN IF NOT EXISTS lookup_locked_until DATETIME NULL AFTER lookup_failed_attempts;
+
+ALTER TABLE inquiries
+  DROP INDEX IF EXISTS idx_inquiries_retention,
+  ADD INDEX idx_inquiries_retention (closed_at, deleted_at);