Changed-files summary table in the unified review comment

[JSONbored]

Phase 1 — Review output, noise & trust

Context

The unified review comment shows the readiness table and the AI advisory but no per-file change overview. We already classify files (src/signals/path-matchers.ts) and build a prioritized diff (src/review/review-diff.ts).

Goal

A grouped, deterministic changed-files summary table in the unified comment.

Requirements

• Deterministic: group changed files by type (source/test/docs/config/generated via path-matchers), collapse large same-type groups into one row, show +/- counts.
• Rendered as a collapsible section in src/review/unified-comment.ts; display gated by review.changed_files_summary (default off). No AI.

Deliverables

• Renderer + grouping logic + tests; manifest toggle + docs.

Expected outcome

• Maintainers grasp PR shape at a glance; less scrolling on multi-file PRs.

Effort

M.

[linear-code]

JSO-2037