fix(viewer): wrap long session metadata on mobile

[dvd233]

Summary

Implements item 2 from #1455: long CWD and branch metadata now wraps instead of being clipped on narrow screens.

• keep the existing single-line metadata behavior on desktop
• allow flex metadata values to wrap at arbitrary path boundaries below 768px
• avoid overflow: hidden and ellipsis clipping for the wrapped values
• extend the existing CSS cascade contract test

Testing

• go test ./internal/viewer — passed
• go vet ./internal/viewer — passed
• go build ./cmd/opencodereview — passed
• gofmt and git diff --check — passed
• make check, make test, project ocr review, and browser-width verification were not available in this Windows environment (Make, the ocr binary, and Playwright/browser runtime are not installed)

AI disclosure: Codex (GPT-5) assisted with issue analysis and patch preparation. The complete diff and test results were reviewed before submission.

Fixes #1455

[github-actions]

🔍 OpenCodeReview found 1 issue(s) in this PR.

• ✅ Successfully posted inline: 1 comment(s)

[github-actions]

flex-wrap: wrap has no practical effect here. Each .meta span uses display: flex (from the base rule at line 417), but its children are inline elements (<strong>, <code>, text nodes) that don't participate in flex wrapping. The actual text wrapping on narrow screens is already achieved by white-space: normal and overflow-wrap: anywhere. Consider removing this property to avoid confusion for future maintainers.

[lizhengfeng101]

LGTM