Support multi-line startup commands in Terminal settings

Location: Settings > Terminal > Commands > Add Command

Description:
Currently, the Command field in Terminal settings only supports entering a single-line command. This is limiting for workflows that require running multiple setup commands in sequence when starting a custom terminal.

For example, I want to create a custom startup command that runs several OpenClaw commands:

openclaw doctor --generate-gateway-token
systemctl --user restart openclaw-gateway.service
openclaw dashboard --no-open

At the moment, there does not appear to be a clear way to enter this as a multi-line command block directly in the Add Command dialog.

Expected:
- The Command field should support multi-line input, or provide a dedicated command sequence mode.
- Users should be able to define several commands that run in order when the terminal starts.
- The UI should preserve line breaks and make it clear whether commands are executed sequentially in the same shell session.

Actual:
- The Add Command dialog appears to accept only a single-line command.
- Users who need multiple commands must find workarounds, such as creating an external script or manually running the commands after opening the terminal.

Impact:
This limits custom terminal presets for tools that require a multi-step startup process. It also makes setup flows less convenient for services that need token generation, service restart, and dashboard launch commands before they are ready to use.