feat(app): support bidirectional chat text

[miladjs]

Issue for this PR

Closes#32726

Related: #35319 and #37249

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds dir="auto" to user-message text and both the legacy and v2 prompt editors.

The browser determines direction from the first strong character, so Persian, Arabic, and Hebrew text renders RTL while English remains LTR. Mixed RTL/LTR text continues to use the browser's Unicode bidirectional handling.

This complements #37249, which handles rendered Markdown and tables but was opened before the current v2 prompt input was added.

How did you verify your code works?

• Ran the session-ui test suite: 75 tests passed.
• Ran type checking for packages/session-ui and packages/app.
• Ran the full pre-push type check across 30 packages.
• Verified Persian and English text use the expected direction in user messages and the prompt editor.

Screenshots / recordings

Before/after examples of the RTL rendering issue are available in #35319.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

The PR #37249 appears in the results, which is already mentioned in the current PR's description as a related PR. Since PR #38079 is the current PR and #37249 is explicitly noted as related (handling rendered Markdown and tables while this PR handles the prompt editor), these are complementary changes rather than duplicates.

No duplicate PRs found

[github-actions]

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