feat: improve Resume Conversation UX on mobile

[TeigenZhang]

Summary

On narrow screens the Resume Conversation list on the welcome page was hard to scan: the first prompt was clipped almost immediately by a single-line layout, and the working-dir subtitle was truncated at the end — exactly where the identifying project name lives. The ~/ shorthand also never fired on macOS because only /home/ was handled.

This PR reworks the history item layout without changing the API:

• Title switches to a 2-line clamp so more of the first prompt is visible.
• Subtitle is now case-aware: workingDir is matched against loaded cases (incl. linked cases). Exact matches render as #caseName, subpaths as #caseName/sub, otherwise it falls back to the directory basename. # labels are styled in accent blue.
• Home shorthand now normalizes both /home/<user>/ and /Users/<user>/ to ~/ so macOS paths are collapsed.
• Inline detail toggle: each item gets a ⋯ button that expands an in-place panel with the full prompt, full path, timestamp, size, and short session id. Click again to collapse. Clicking the card body still triggers resume; the toggle uses stopPropagation to avoid accidental resume. The chevron rotates 90° in the expanded state.

Also fixes a small CSS bug where .history-item-detail used display: flex and therefore defeated the HTML hidden attribute's default display: none — an explicit [hidden] override was added.

Test plan

• Verify default render: title clamps to 2 lines, subtitle shows #case label when a case matches, basename otherwise.
• Verify detail panel is collapsed by default.
• Click ⋯ → panel expands with full prompt/path/meta. Click again → collapses.
• Click card body (outside the button) → resume flow still runs.
• macOS /Users/<me>/... paths display as ~/... in the detail panel.
• npm run build succeeds; assets rehash cleanly.

🤖 Generated with Claude Code

[Ark0N]

Reviewed and verified locally on a mobile viewport (iPhone 13):

• Typecheck + lint clean; CI green
• Helper functions handle all edge cases: longest-prefix-wins for nested cases, basename fallback, null/empty safety, both Linux /home/<user>/ and macOS /Users/<user>/ normalized to ~/
• Linked cases are picked up automatically since /api/cases merges them into the same {name, path} shape
• Live UI: detail panel hidden by default, expand toggles aria-expanded/expanded class/visibility cleanly, collapse works, no console errors
• The [hidden] CSS override is the correct fix for display: flex defeating the HTML hidden attribute

Nice work — the 2-line title clamp + #caseName subtitle + collapsible detail panel makes the welcome list much more readable on narrow screens. Thank you!