style(design): F-007 — bring PR list rows to parity with issues

The PR list showed only 'branch -> main' + a status badge, while issue rows
carry a status glyph, title, author and age. Render PRs with the same
.issue-row structure: state-colored glyph, source->target title, status
badge, and a meta line (#N, opened by author, age, version).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>