feat(postgres): in-panel backup/restore and consistent CLI backend

Two PostgreSQL gaps on the panel:

1. x-ui setting and other CLI subcommands read XUI_DB_TYPE/XUI_DB_DSN from
   the process environment, which systemd injects via EnvironmentFile but a
   plain shell invocation does not. On a PostgreSQL install the CLI silently
   fell back to SQLite, so changes made from the management menu never
   reached the panel's database. Load the systemd EnvironmentFile
   (/etc/default/x-ui and distro equivalents) at startup; godotenv.Load does
   not override existing vars, so it stays a no-op for the managed service.

2. DB backup/restore (panel endpoints and the Telegram bot) only handled the
   SQLite file, so on PostgreSQL Back Up returned a stale/absent x-ui.db and
   Restore silently did nothing. Add pg_dump/pg_restore based backup/restore:
   - GetDb/ImportDB run pg_dump (custom format) / pg_restore, passing
     credentials via the PG* environment instead of argv.
   - getDb downloads x-ui.dump on Postgres, x-ui.db on SQLite.
   - Telegram backup sends the matching file via GetDb.
   - BackupModal shows a Postgres note and accepts .dump; the dist page
     injects window.X_UI_DB_TYPE; new strings translated for all locales.
   - install.sh installs postgresql-client for the external-DSN path and
     points the user to in-panel Backup & Restore.

Closes #4658

.github/workflows/claude-issue-bot.yml

@@ -16,6 +16,7 @@ jobs:
       - uses: actions/checkout@v6
       - uses: anthropics/claude-code-action@v1
         with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
           claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
           claude_args: "--max-turns 25"
           prompt: |