feat: Add message queueing while AI is processing

[roomote]

Summary

Implements #6287 - Adds the ability to queue chat messages while the AI is taking its turn, allowing users to steer the output without interrupting it.

Changes

• ChatTextArea Component:

  • Updated send button to show a queue icon (ListPlus) when sending is disabled
  • Modified button behavior to queue messages instead of being disabled
  • Added appropriate tooltips and aria-labels for accessibility

• QueuedMessages Component:

  • Enhanced UI with truncated message previews (50 char limit)
  • Added inline edit functionality with Edit2 icon
  • Improved styling with borders, hover effects, and better visual hierarchy
  • Added support for showing image count in queued messages

• Translations:

  • Added new translation keys for queue-related UI text
  • Updated existing keys to support message count display

Testing

• All existing tests pass (850 tests)
• Updated ChatView test suite to cover new queueing behavior
• Fixed mock component props to match actual implementation

Screenshots

The queue icon appears when AI is processing:

• Send button shows ListPlus icon instead of Send icon
• Tooltip changes to "Queue message"
• Messages are added to queue and displayed with truncated previews

Closes #6287

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Important

Adds message queueing functionality to the chat interface, allowing users to queue messages while the AI is processing, with UI and test updates.

• Behavior:
  • ChatTextArea now shows a queue icon (ListPlus) when sending is disabled, allowing messages to be queued.
  • QueuedMessages component displays queued messages with truncated previews and allows inline editing.
• UI Components:
  • Updated ChatTextArea.tsx to modify button behavior and tooltips for queueing.
  • Enhanced QueuedMessages.tsx with styling improvements and image count display.
• Translations:
  • Added translation keys for queue-related UI text in chat.json.
• Testing:
  • Updated ChatView.spec.tsx to include tests for message queueing behavior.
  • Ensured all existing tests pass and mock components are updated.

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[daniel-lxs]

This is already implemented