The jar's ka-vs-close throughput inversion was observed on the box but its
run configuration died with the job workspaces, so it can't be re-derived —
this commit makes the comparison a committed, controlled experiment instead
of a lost one-off.
- examples/plain_serve: the load_profile request path with zero causal
machinery (same route/handler/Config), serving until killed. The plain
half of the A/B; throughput measured externally by wrk.
- scripts/ka-close-matrix.sh: {ka,close} x {plain,causal} on fresh ports,
byte-identical wrk args per mode pair except the Connection: close
header, disjoint-core pinning for server vs wrk, per-cell curl
verification of the negotiated connection behavior, ss/env capture, and
a parsed summary with a close/ka ratio verdict. The causal cells double
as the forgiveness-fix box validation (v13 pending item, pull-forward
agreed): key on forgiven staying ~ injected x parked-actors in
close-mode churn, not process-lifetime phantoms.
