Verify at code level that the Phase 1/2 review findings were actually
closed (not just self-reported): icon cache concurrency + LRU + bounded
fetch (T-606), UI-thread icon delivery (T-607), install durability with
Windows FlushFileBuffers / POSIX dir sync (T-613), ZIP central-directory
preflight (T-612), and catalog signature cross-impl vectors (T-614).
All confirmed real. Records three residuals (R1 real power-loss
validation, R2 per-file fsync cost, R3 singleflight ctx caveat).
Also gitignore *.code-workspace (per review recommendation).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>