3038c94b8c
Merges practical items from resilience Phases C+D+E+F into one pass. Turns all 6 remaining RED tests GREEN: - D1/D2: Health check timeout + parallel join_all - C6: Fix recursive CAS calculate_size() - C7: FUSE read 30s timeout wrapper - 6.4: Auto-re-fetch corrupt/missing chunks from origin - 6.6: Passthrough fallback when CAS write fails - C9: PID file with flock - 5.3: fd exhaustion graceful handling ~4 days estimated.