feat(response-viewer): ASCII diagram wrap toggle, mobile code blocks, chrome-stripping fallback

[TeigenZhang]

Summary

Seven small commits that polish the Response Viewer (merged in #62) for daily use on mobile and desktop:

• Card-style message separation + table wrap (89a79a3) — messages get bordered cards; tables wrap in a horizontal-scroll container so they don't collapse on narrow viewports.
• ANSI/CLI-chrome stripping fallback (30b802b) — when the JSONL transcript isn't available, the viewer falls back to the terminal buffer; strip ANSI CSI/OSC/DCS, status bar, hints, spinner, and progress-bar glyphs so what the user sees is conversational text, not the TUI. Also captures the Claude CLI's real session ID for transcript lookup.
• Mobile code-block wrap (0bb4b85) — regular code blocks wrap on mobile by default (no more sideways scroll for every snippet); ASCII diagrams stay rigid with a horizontal scroll hint.
• Per-block wrap toggle (440b5c0) — add a toggle button on code blocks identified as ASCII diagrams so the user can flip between wrap (readable) and horizontal scroll (structure preserved).
• Wrap-by-default + pinned toggle button (dfe1dd9) — wrap is now the default; the toggle button lives outside the <pre> scroll container so it stays pinned to the visual right edge even while scrolling horizontally.
• Narrow diagram detection (e777ed9) — only box-drawing (─-╿) and block elements (▀-▟) trigger the diagram toggle. Previously arrows and geometric shapes in prose caused false positives.
• Desktop eye icon (49139d3) — the Response Viewer entry point now shows on desktop too (was mobile-only).

All changes are additive to _renderMarkdown / _cleanTerminalBuffer / _preprocessAsciiArt in app.js plus scoped CSS under .rv-* in styles.css. _sanitizeHtml (introduced in master) is still applied to markdown output.

Test plan

• Narrow mobile viewport: regular code blocks wrap, long responses scroll vertically only
• ASCII diagram block shows wrap toggle; clicking flips wrap ↔ horizontal scroll
• Table in response wraps in a scroll container instead of overflowing
• When transcript file is missing, viewer shows clean conversation text (no ANSI, no TUI chrome)
• Desktop browser shows the eye icon next to session tabs
• npm run typecheck / npm run lint / npm run build pass

[Ark0N]

Thanks @TeigenZhang for this — the polish on mobile, the chrome-stripping fallback, and the wrap-toggle button are all great improvements.

Before merging I pushed one fix commit (bdcd808) addressing two issues in _renderMarkdown:

1. src is not defined — the new code passes src to _preprocessAsciiArt but the parameter is text. The try/catch swallowed the ReferenceError, so _renderMarkdown always fell through to the plain-text <pre> branch. The new table-wrap, diagram-toggle, and ASCII preprocessing never actually ran in practice. ESLint can't catch this because src/web/public/app.js is in the eslint ignore list.
2. XSS regression — the description says _sanitizeHtml "is still applied", but the function was deleted in the refactor and the call removed, so marked.parse() output went straight into innerHTML unsanitized. Restored the helper and re-applied it before the table-wrap / diagram-toggle post-processing.

npm run typecheck and npm run build pass after the fix. Merging now.