CAS analytics no longer fsyncs per op, ending the daemon’s disk stall

The CAS daemon’s per-op analytics SQLite database now opens with PRAGMA synchronous = OFF instead of NORMAL, so the metadata insert fired after every artifact op no longer fsyncs. On shared or contended disks (notably hosted Tart VM roots) this previously starved the daemon’s load / decompress tasks and inflated per-op CAS latencies. The artifact transfer and codec durations are now recorded alongside the total so the per-op time budget can be broken down post-hoc.