fix: Disable Send/Submit Button by Default in Chat Section

[Prasanjeet-Microsoft]

Purpose

• The purpose of this PR is to modify the chat UI such that the "Send" button is disabled by default. It will only be enabled once the user enters text into the chat input field. This behavior improves the user experience by preventing users from sending empty messages

Does this introduce a breaking change?

• Yes
• No

Golden Path Validation

• I have tested the primary workflows (the "golden path") to ensure they function correctly without errors.

What to Check

Verify that the following are valid:

The Send button is disabled by default.
The Send button becomes enabled when text is entered.
No breaking changes are introduced in the chat feature.