Add input box font size setting

[xujingli]

Description

Closes #3668

This PR adds a separate Input Box Font Size setting under General Settings.

Main changes:

• Adds inputBoxFontSize to the settings schema and defaults, with a default value of 14.
• Adds a new slider in General Settings for configuring the input box font size.
• Renames the existing display font slider label to Chat Font Size, so it is clearer that it controls chat/message text.
• Applies the configured input box font size to the message input textarea instead of using the previous hardcoded 14px.

Additional Notes

Validation:

• Ran pnpm exec biome check on the changed files. It completed successfully, with only pre-existing warnings in touched files.
• Ran pnpm exec tsc --noEmit --pretty false; the repository currently has unrelated baseline TypeScript errors on main.

Screenshots

N/A

Contributor Agreement

By submitting this Pull Request, I confirm that I have read and agree to the following terms:

• I agree to contribute all code submitted in this PR to the open-source community edition licensed under GPLv3 and the proprietary official edition without compensation.
• I grant the official edition development team the rights to freely use, modify, and distribute this code, including for commercial purposes.
• I confirm that this code is my original work, or I have obtained the appropriate authorization from the copyright holder to submit this code under these terms.
• I understand that the submitted code will be publicly released under the GPLv3 license, and may also be used in the proprietary official edition.

Please check the box below to confirm:

[x] I have read and agree with the above statement.

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: efc14a5c-2513-469c-af80-7e9ba2ea8fc9

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}