fix(app): restore ChatView code block styling

[Itsnotaka]

What changed

• Restored the former ChatView fenced-code geometry through Honk's Prose tokens: 12px inset, 8px radius, and 12px/18px mono type.
• Removed the assistant code-line gutter and its per-line number nodes.
• Made Pierre-backed read/write previews use the same Honk-owned frame and inset while leaving patch diff gutters unchanged.
• Added focused structural and geometry tests plus a dev-time performance review.

Why

The current implementation mixed an editor-style line-number gutter into assistant prose and let Pierre choose source-preview spacing. Former ChatView used Pierre only for highlighted token spans and owned the code-block frame itself.

Performance

• A 100-line streaming fence drops from 200 line-related spans to zero.
• The eager startup graph stays at 105 modules and 869.9 KiB.
• First-load assets are 53 raw bytes and 29 gzip bytes smaller.
• The lazy thread chunk is 402 raw bytes and 212 gzip bytes smaller.

Checks

• 23 focused app tests pass.
• 4 focused Prose tests pass.
• App production build passes.
• UI typecheck passes.
• Exact root pnpm dev starts Electron, the renderer, and a healthy sidecar.
• React Doctor reports no new changed-file issue.

App typecheck, design lint, and the architecture check still report the known main-branch onboarding, dormant v2, and oversized-file debt. None is in this change.

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Project	Deployment	Actions	Updated (UTC)
honk-marketing	Ready	Preview	Aug 4, 2026 8:16pm