feat(cli): implement uninstall command and add log-level option

- Implement 'astrbot uninstall' to remove systemd service and data files
- Add '--log-level' option to 'astrbot run' (default: INFO)
- Pass log level config to core logger via env var

scripts/astrbot.service

@@ -1,5 +1,7 @@
+# user service
 [Unit]
 Description=AstrBot Service
+Documentation=https://github.com/AstrBotDevs/AstrBot
 After=network-online.target
 Wants=network-online.target
 
@@ -9,6 +11,9 @@ WorkingDirectory=%h/.local/share/astrbot
 ExecStart=/usr/bin/sh -c '/usr/bin/astrbot run || { /usr/bin/astrbot init && /usr/bin/astrbot run; }'
 Restart=on-failure
 RestartSec=5
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=astrbot-%u
 Environment=PYTHONUNBUFFERED=1
 
 [Install]