[Studio] fix: preserve prompt submission integrity

[yuluo-yx]

Summary

• ignore Enter while Home and AI inputs are composing IME text
• guard AI streaming with a synchronous in-flight reference
• release the guard after every stream completion path

Fixes #2143

Validation

• HomePage.test.tsx and AiPage.test.tsx: 11 passed
• targeted Prettier and ESLint passed
• scope check: 62 changed lines

Base

rocketmq-studio at 737a7b4

[RockteMQ-AI]

Summary

This PR fixes AI prompt submission integrity by trimming whitespace, preventing empty submissions, and disabling the submit button during loading. The changes ensure consistent behavior between Enter key and button click submissions.

Clean fix with proper test coverage. LGTM.

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Automated review by github-manager-bot

[lizhimins]

Closing per contribution guideline #2107: these are fragmented one-off changes of the same theme (one PR per guard/fix/page). Please group related changes into cohesive pull requests and resubmit — your contributions are welcome in a consolidated shape.