🎨 Palette: Add clear disabled states and tooltips when offline

[teerthsharma]

💡 What:
Disabled the chat input and send button when the tunnelStatus is not 'LOCKED' (offline). Updated the input placeholder, button title, and aria-labels dynamically to explain that the kernel is offline and waiting for a connection.

🎯 Why:
Previously, users might try to send messages while the kernel was offline without receiving immediate feedback that their input wouldn't be processed. By visibly disabling the inputs and providing explicit reasons (via placeholders and tooltips) for why they are disabled, we remove confusion and make the system's state much clearer and more intuitive.

📸 Before/After:
(Visual change: The input field now reads "Kernel offline. Waiting for connection..." and both the input and button appear grayed-out/disabled when offline instead of looking interactive.)

♿ Accessibility:
Coupled the visual disabled:opacity-50 disabled:cursor-not-allowed styles with dynamic aria-label and title attributes on both the input and submit button. This ensures that screen reader users and mouse users hovering over the elements understand precisely why the interactive elements are currently disabled.

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PR created automatically by Jules for task 13066326533245901586 started by @teerthsharma

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