feat(web): add word wrap to file source previews

[techotaku39]

Summary

• Add a word-wrap toggle to source-mode file previews.
• Reuse the existing hapi-code-wrap preference used by conversation detail code surfaces.
• Preserve the preference across reloads, sessions, tabs, and windows on the same origin.
• Preserve syntax highlighting and horizontal scrolling when wrapping is disabled.
• Add regression coverage for persisted state, toggle behavior, and source rendering.
• No API, data, dependency, or migration changes.

Problem / Motivation

Source-mode file previews currently render long lines using horizontal scrolling and do not expose the existing word-wrap control. This makes large files difficult to read on narrow screens and makes file previews inconsistent with conversation detail code blocks.

Validation

• bun typecheck — passed.
• bun run --cwd web test -- src/routes/sessions/file.test.tsx src/components/CodeBlock.test.tsx src/components/assistant-ui/shiki-highlighter.test.tsx src/components/assistant-ui/markdown-text-codeblock.test.tsx src/hooks/useCodeWrap.test.ts — 5 files, 32 tests passed.
• pwsh -NoProfile -File .\scripts\Invoke-HapiTaskPlaywright.ps1 -Name file-preview-code-wrap -Suite Root -TestArgs terminal-wrap-fidelity.spec.ts — 2/2 passed.
• bun run build — passed.
• Full Live Playwright verification through the task wrapper — 3/3 passed:
  • Desktop source preview toggle and reload persistence.
  • Mobile classic scrollbar wrapping without horizontal overflow.
  • Mobile overlay scrollbar wrapping without horizontal overflow.
• git diff --check — passed.

Related Issues

Refs #1074

AI Disclosure

OpenAI Codex assisted with the implementation and validation. Model: GPT-5.6.

[github-actions]

Findings

• None.

Summary
Review mode: initial. No Blocker, Major, Minor, or Nit issues found in the added/modified lines. The source preview uses the existing shared wrap preference, retains the unwrapped horizontal-scroll path, and keeps the syntax-highlighted content inside the styled pre element. Residual testing risk: the added unit test mocks the Shiki renderer and cannot validate real highlighted DOM or narrow-viewport overflow geometry.

Testing

• Not run (automation); static review only.
• GitHub checks at review time: integration passed; test pending.

HAPI Bot