[CLNP-6663] fix: improve message validation related to mentionedMessageTemplate

[OnestarLee]

External Contributions

This project is not yet set up to accept pull requests from external contributors.

If you have a pull request that you believe should be accepted, please contact
the Developer Relations team [email protected] with details
and we'll evaluate if we can setup a CLA to allow for the contribution.

For Internal Contributors

[CLNP-6663](https://sendbird.atlassian.net/browse/CLNP-6663)

Description Of Changes

Added validation for the mentionedMessageTemplate API, as it was moved from BaseMessage to UserMessage in Chat SDK v4.16.4.

Types Of Changes

What types of changes does your code introduce to this project?
Put an x in the boxes that apply_

• Bugfix
• New feature
• Documentation (correction or otherwise)
• Cosmetics (whitespace, appearance (ex) Prettier)
• Build configuration
• Improvement (refactor code)
• Test

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 11.49%. Comparing base (6fcbc23) to head (4ed0b24).

Files with missing lines	Patch %	Lines
...ges/uikit-react-native/src/libs/MentionManager.tsx	0.00%	5 Missing ⚠️
...ikit-react-native/src/hooks/useMentionTextInput.ts	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #236      +/-   ##
==========================================
- Coverage   11.50%   11.49%   -0.01%     
==========================================
  Files         358      358              
  Lines        8485     8489       +4     
  Branches     2253     2377     +124     
==========================================
  Hits          976      976              
+ Misses       7508     7438      -70     
- Partials        1       75      +74     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Copilot]

Pull Request Overview

This PR improves message validation by ensuring the proper handling of the mentionedMessageTemplate property, which has been moved from BaseMessage to UserMessage in Chat SDK v4.16.4.

• Updated validation in MentionManager to use the in-operator for checking the existence of mentionedMessageTemplate.
• Refined the conditional extraction of the mentionedMessageTemplate value in useMentionTextInput.

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
packages/uikit-react-native/src/libs/MentionManager.tsx	Updated validation logic to check for the existence of the mentionedMessageTemplate property before using it.
packages/uikit-react-native/src/hooks/useMentionTextInput.ts	Modified the extraction logic for mentionedMessageTemplate using a conditional check to ensure proper fallback handling.

Files not reviewed (1)

• package.json: Language not supported

[bang9]

lgtm!