feat: integrate platform backend and application interfaces

server/migrations/0011_v1_webdav_retention_state.sql

@@ -0,0 +1,9 @@
+ALTER TABLE webdav_configs
+  ADD COLUMN IF NOT EXISTS retention_state TEXT NOT NULL DEFAULT 'active';
+
+ALTER TABLE webdav_configs
+  DROP CONSTRAINT IF EXISTS webdav_configs_retention_state_check;
+
+ALTER TABLE webdav_configs
+  ADD CONSTRAINT webdav_configs_retention_state_check
+  CHECK (retention_state IN ('active', 'deleting', 'deleted', 'error'));