fix(ui): improve edit control ux, no layout shift, consistent spacing

[adelindanaila]

Summary

• ensured consistent spacing, prevent layout shift, basic theme.ts config

Scope

• User-facing/API changes: Edit/Add Control modal only: improved spacing and no layout shift when toggling Form/JSON or when validation state appears.
• Internal changes: New ui/src/theme.ts with default form-input label styles;
• Out of scope:

Risk and Rollout

• Risk level: low
• Rollback plan: revert

Testing

• Added or updated automated tests
• Ran make check (or explained why not)
• Manually verified behavior

Checklist

• Linked issue/spec (if applicable)
• Updated docs/examples for user-facing changes
• Included any required follow-up tasks

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[siddhant-galileo]

hey @adelindanaila , can you pls attach screenshot to highlight the changes made. thanks