🎨 Palette: Disable inputs when kernel offline

[teerthsharma]

💡 What: Disabled the main chat input field and submit button when the tunnelStatus is not 'LOCKED'.
🎯 Why: To prevent users from attempting to interact with the system or losing typed messages when the kernel is temporarily disconnected or re-establishing connection.
📸 Before/After: Before, the input remained enabled and users could attempt to send messages that would fail if offline. After, the input is explicitly grayed out with a clear "Connecting to kernel..." message.
♿ Accessibility:

• Added standard disabled:cursor-not-allowed styles for visual feedback.
• Dynamically updated the placeholder, aria-label, and title attributes so screen readers and mouse hover users have a clear understanding of why the form is disabled.

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PR created automatically by Jules for task 17585996939814965598 started by @teerthsharma

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