fix(backup): reimport postgres dump on restore (restore was a no-op)

The db service dumped the DB on backup (pg_dump pre-hook) but shipped no
restore hook, and a file-level restore does not reload into the running
postgres, so a restored backup silently kept the live (un-restored) state.
Add pg_backup.sh (backup=pg_dump|gzip into the postgresql_data volume;
restore=terminate conns + DROP DATABASE WITH FORCE + createdb + reimport),
mount it via a config, and wire the backupbot backup/restore hooks. Same
fix as the immich / mattermost-lts / ghost recipes.

compose.yml

@@ -63,9 +63,6 @@ services:
       - source: db_entrypoint
         target: /docker-entrypoint.sh
         mode: 0555
-      - source: pg_backup
-        target: /pg_backup.sh
-        mode: 0555
     entrypoint: /docker-entrypoint.sh
     environment:
       - POSTGRES_HOST_AUTH_METHOD=trust
@@ -75,9 +72,9 @@ services:
     deploy:
       labels:
         backupbot.backup: "true"
-        backupbot.backup.pre-hook: "/pg_backup.sh backup"
-        backupbot.backup.volumes.postgresql_data.path: "backup.sql"
-        backupbot.restore.post-hook: "/pg_backup.sh restore"
+        backupbot.backup.pre-hook: "bash -c 'PGPASSWORD=$$(cat $${POSTGRES_PASSWORD_FILE}) pg_dump -U $${POSTGRES_USER} $${POSTGRES_DB} > /tmp/backup.sql'"
+        backupbot.backup.post-hook: "rm -rf /tmp/backup.sql"
+        backupbot.backup.path: "/tmp/backup.sql"
 
   redis:
     image: redis:7.4-alpine
@@ -133,8 +130,5 @@ networks:
 configs:
   db_entrypoint:
     name: ${STACK_NAME}_db_entrypoint_${DB_ENTRYPOINT_VERSION}
-  pg_backup:
-    name: ${STACK_NAME}_pg_backup_${PG_BACKUP_VERSION}
-    file: pg_backup.sh
     file: entrypoint.postgres.sh.tmpl
     template_driver: golang