[ENHANCEMENT] Chat input textarea font size not controlled by "Chat Font Size" setting

[AmitTzah]

Problem (one or two sentences)

The chat input box font is tiny and doesn't scale with the Chat Font Size setting. That setting only changes assistant message text.

Context (who is affected and when)

Happens every time you type a message. Affects anyone using the chat, especially with larger font preferences.

Desired behavior (conceptual, not technical)

Input box and user messages should scale with font size too, either through the existing slider or a separate one.

Constraints / preferences (optional)

No response

Request checklist

• I've searched existing Issues and Discussions for duplicates
• This describes a specific problem with clear context and impact

Zoo Code Task Links (optional)

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Acceptance criteria (optional)

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Proposed approach (optional)

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Trade-offs / risks (optional)

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