* feat: render Reviews page diffs with pierre MultiFileDiff
The Reviews detail page used a hand-rolled hunk renderer with no syntax
highlighting. Switch it to the same pierre MultiFileDiff + theming the agent
chat git panel uses.
- review-diff API now returns full original/modified file contents instead of
hunks, via a shared build_pr_diff_files helper extracted from thread_api
- findings render as right-anchored markers (pierre line annotations); focus
highlight uses selectedLines; floating finding card still anchors to the marker
* feat: auto-collapse a review diff card when marked as viewed
* fix: URL-encode file path in Contents API fetch
Filenames containing reserved URL characters (#, ?) were truncated, so those
files rendered as empty/unrenderable. quote(path, safe='/') preserves the path
separators while escaping the rest.
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Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>
