Feature/genai disable empty input

[ganievs]

Issue

Closes #469

Reason for this change

Users could send empty messages or messages containing only whitespace in the AI chat interface, causing model validation errors:

• Error: The model returned the following errors: messages: text content blocks must contain non-whitespace text
• Error: Invalid message content: empty string. 'human' must contain non-empty content.

This occurred when users clicked Send or pressed Enter without typing actual content, resulting in confusing error messages and poor UX.

Description of changes

Added client-side validation in ChatInputComponent to prevent submission of empty or whitespace-only messages:

1. Send button validation: Modified the Send button's disabled prop to check if the message contains non-whitespace content using !message.trim()
2. Enter key validation: Updated the checkKeyPress handler to validate message content (message.trim()) before processing Enter key submission

The fix ensures that:

• The Send button is disabled when the input is empty or contains only whitespace
• Pressing Enter without non-whitespace content does not trigger submission
• Shift+Enter continues to work normally for multi-line input

Description of how you validated changes

Manual testing performed:

• Verified Send button is disabled with empty input
• Verified Send button is disabled with whitespace-only input (spaces, tabs, newlines)
• Verified Send button enables with actual text content
• Confirmed Enter key does not submit empty messages
• Confirmed Enter key does not submit whitespace-only messages
• Confirmed Shift+Enter still creates new lines
• Verified no model validation errors occur after fix
• Tested message submission still works correctly with valid content

No unit tests added as this is a UI interaction fix in an existing component without test coverage.

Checklist

• My code adheres to the CONTRIBUTING GUIDE

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license