fix(frontend): Disable terminal stdin if the runtime is starting up

[amanape]

End-user friendly description of the problem this fixes or functionality that this introduces

• User could submit commands before the runtime is active, causing a fatal error

• Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

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Give a summary of what the PR does, explaining any non-trivial design decisions

• Disable stdin until the runtime is active
• A small indicator on the terminal label that shows whether the terminal is enabled or disabled (based on runtime status)
  

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Link of any specific issues this addresses
Resolves #5557

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:2126a8e-nikolaik   --name openhands-app-2126a8e   docker.all-hands.dev/all-hands-ai/openhands:2126a8e

[enyst]

Thanks!