ci: add revert migration test

.gitlab-ci.yml

@@ -78,6 +78,7 @@ test:build:
     - pnpm install --frozen-lockfile
     - pnpm run build:debug
     - pnpm run migrate
+    - psql --host postgres --user "${POSTGRES_USER}" --dbname "${POSTGRES_DB}" --command "$(cat docs/downgrade.sql)"
 
 test:build:backend_ts_only:
   stage: test
@@ -93,6 +94,7 @@ test:build:backend_ts_only:
           - package.json
           - Cargo.toml
           - Cargo.lock
+          - docs/downgrade.sql
       when: never 
     - if: $CI_COMMIT_BRANCH == 'develop' || $CI_MERGE_REQUEST_TARGET_BRANCH_NAME == 'develop'
       changes:
@@ -118,6 +120,7 @@ test:build:backend_ts_only:
     - pnpm install --frozen-lockfile
     - pnpm --filter 'backend' --filter 'firefish-js' --filter 'megalodon' run build:debug
     - pnpm run migrate
+    - psql --host postgres --user "${POSTGRES_USER}" --dbname "${POSTGRES_DB}" --command "$(cat docs/downgrade.sql)"
 
 test:build:client_only:
   stage: test

docs/downgrade.md

@@ -1,10 +1,11 @@
 # Downgrading to `v20240206`
 
-## systemd
+## systemd/pm2
 
 1. Stop the Firefish service
     ```sh
     sudo systemctl stop your-firefish-service.service
+		# or pm2 stop firefish
     ```
 1. Take a backup
 1. Revert database migrations
@@ -22,7 +23,7 @@
     ```
 1. Switch back to the `v20240206` tag
     ```sh
-    git switch v20240206
+    git switch --detach v20240206
     ```
 1. Rebuild Firefish
     ```sh
@@ -32,6 +33,7 @@
 1. Start the Firefish service and confirm that Firefish is downgraded
     ```sh
     sudo systemctl start your-firefish-service.service
+		# or pm2 start firefish
     ```
 
 ## Docker/Podman