* fix(ui): override form-render color widget for React 19 compat

* Update packages/ui/src/components/Designer/RightSidebar/DetailView/ColorWidget.tsx

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

* fix(ui): keep color widget output to valid hex

Address review feedback on the React 19 color widget override:

- Default disabledAlpha to true so the picker emits 6-digit hex; fields
  can still opt into alpha with disabledAlpha={false}, where 8-digit hex
  is intentional. Prevents unexpected #rrggbbaa values reaching PDF render.
- Only commit valid hex (or empty to clear) from the free-text input.
  Local state keeps typing responsive while invalid intermediate values
  are kept out of the schema.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>