Arc: Unauthenticated access to Go debug pprof endpoints leaks runtime state and enables CPU-burn DoS

Arc is an open, SQL-native time-series database for telemetry. Versions prior to 26.06.1 register Go's `net/http/pprof` handlers at `/debug/pprof/*` via `app.Use(pprof.New())` in `internal/api/server.go`, and `/debug/pprof` is added to `PublicPrefixes` in `cmd/arc/main.go`. The auth middleware short-circuits before the token check on prefix match, so the endpoints are reachable without any authentication. Version 26.06.1 contains a patch. Some workarounds are available. Block `/debug/pprof*` at a reverse proxy / load balancer in front of Arc, restrict Arc's API port to known-trusted networks via firewall rules, and/or patch the running build: comment out `app.Use(pprof.New())` in `internal/api/server.go` and rebuild.