Rewrites findings.md with how-to section, cleaner summary tables,
and more detailed per-pass results. Fixes relative path for
sonarr/radarr API key files after runbook moved deeper in repo.
~16T freed on aya01 (92% → 57% mergerfs pool). Documents root cause
(no hardlinks across mergerfs due to cross-device mounts), cleanup
passes via Sonarr/Radarr API verification, and pending decisions
(Bleach remux, 111 skipped Sonarr entries).
