feat(review): migrate all-files code review to Pierre CodeView (#885)

Replaces the all-files renderer with Pierre's virtualized CodeView (one scroller, identical look, scales to huge diffs); deletes the legacy AllFilesDiffView/LazyFileDiff and their flag; single-file panels stay on FileDiff. @pierre/diffs pinned exact 1.2.8 (1.2.9's tree is broken on npm — see #880).

Also ships: diff staleness detection ('Diff out of date · Refresh' toolbar notice backed by shared per-VCS fingerprints + GET /api/diff/fresh on both Bun and Pi servers), a stale-content guard so files edited mid-review degrade to raw-patch view instead of breaking virtualization, the Ask AI wrong-file fix (pre-existing), and toolbar/header UI polish (global settings cog, aligned sem badges, no all-files split dragger).

Hardened through five review waves; tested with 1384 passing tests incl. real-git fingerprint and patch-consistency suites. Known minor gaps documented in the PR.

package.json

@@ -39,7 +39,7 @@
     "@anthropic-ai/claude-agent-sdk": "^0.2.92",
     "@openai/codex-sdk": "^0.118.0",
     "@opencode-ai/sdk": "^1.3.0",
-    "@pierre/diffs": "1.1.20",
+    "@pierre/diffs": "1.2.8",
     "diff": "^8.0.4",
     "dockview-react": "^5.2.0",
     "dompurify": "^3.3.3",