feat(code): use Quill Chip for mention chips + PromptInput story

[adamleithp]

Summary

• Replace custom <span>/<button> mention chips with Quill <Chip> component for design system consistency
• Add icon/close crossfade on left side of each chip — type icon fades to X on hover (150ms ease, respects prefers-reduced-motion)
• Add selection ring when arrow-keying through chips in the editor
• Add cursor-pointer only on chips with click actions (github_issue, pastedText), cursor-default on others
• Add comprehensive PromptInput.stories.tsx with real tiptap editor, real UnifiedModelSelector/ReasoningLevelSelector with mock data

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Test plan

• Verify chips render with correct type icons (file, command, github, error, experiment, insight, feature flag)
• Hover chip — icon fades to X, click X removes chip
• Arrow keys through chips — selection ring appears
• GitHub issue chips show cursor-pointer, file/command chips show cursor-default
• PastedText chips show cursor-pointer and expand on click
• Run Storybook — all PromptInput stories render correctly
• Verify no regressions in chip insertion via @ mentions and / commands

🤖 Generated with Claude Code

[greptile-apps]

Prompt To Fix All With AI

This is a comment left during a code review.
Path: apps/code/src/renderer/features/message-editor/components/PromptInput.stories.tsx
Line: 61-69

Comment:
**Chips may be re-inserted on re-render**

`useEffect` runs whenever `chips` reference changes. In Storybook, switching between stories or toggling any control causes a full re-render with a new `chips` array reference, so `insertChip` fires again for each chip already in the editor, producing duplicates. A stable reference (e.g. `useRef` guard or deep-equal comparison) would prevent this.

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "fix: revert pastedText interface change,..." | Re-trigger Greptile}

[greptile-apps]

Chips may be re-inserted on re-render

useEffect runs whenever chips reference changes. In Storybook, switching between stories or toggling any control causes a full re-render with a new chips array reference, so insertChip fires again for each chip already in the editor, producing duplicates. A stable reference (e.g. useRef guard or deep-equal comparison) would prevent this.

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/code/src/renderer/features/message-editor/components/PromptInput.stories.tsx
Line: 61-69

Comment:
**Chips may be re-inserted on re-render**

`useEffect` runs whenever `chips` reference changes. In Storybook, switching between stories or toggling any control causes a full re-render with a new `chips` array reference, so `insertChip` fires again for each chip already in the editor, producing duplicates. A stable reference (e.g. `useRef` guard or deep-equal comparison) would prevent this.

How can I resolve this? If you propose a fix, please make it concise.