🎨 Palette: Disable input during offline state

[teerthsharma]

💡 What: The chat input and send button are now correctly disabled when the system's tunnelStatus is not 'LOCKED'.
🎯 Why: When the Next.js frontend loses connection to the Rust backend daemon, users could previously still type and click send, leading to "ghost interactions" where messages disappeared or failed silently.
📸 Before/After: The input placeholder now explicitly states "System offline. Reconnecting..." when disconnected. The button and input are visibly disabled (opacity-50, cursor-not-allowed).
♿ Accessibility: Added dynamic aria-label and title attributes that update based on the connection status. Screen readers will now announce "Message input (System Offline)" and "Cannot send message while offline", respectively.

---

PR created automatically by Jules for task 8430514719587233668 started by @teerthsharma

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.