cmd/pixad/main.go built the command line and its --config flag, set
PIXA_CONFIG_PATH from that flag, ignored SIGPIPE and started the fx
app. REPO_POLICIES.md now requires cmd/ to hold only one call into
internal/ or pkg/, so that code moves unchanged to Run in the new
internal/app package, and main calls app.Run(Version). Version stays
in main, so the -X main.Version build flags in the Dockerfile and the
Makefile do not change.
Model: opus-5-5
