Drive the RED twin-store pin green: the repair walk now collects its
identity->content mappings into a local last-wins map and appends after
the walk only the entries whose final walk value differs from the
pre-walk snapshot (collect-then-diff-append, decision on #191). The old
per-entry comparison against the mid-walk-stale snapshot appended one
alternating line per scan-triggering lookup while same-identity twins
coexisted — the sidecar now converges to zero growth there too. Lookup
answers (first read_dir match) and verify-on-hit untouched.
Verification: workspace suite 1347 passed / 0 failed; clippy -D
warnings clean.
refs #191
claude
aa94f51d8a