Conform config/deployment/operations to the standard

[next-nf]

Align config loading (today bare-metal-oriented: CONFIG.md/RADIUS.md), deployment packaging, and ops surface to the E18 standard.
Accept: conforms to config/deploy/ops standard.

Epic: next-nf/next-nf#21

Conformance checklist (E18)

• OTP-29 container base (see Port custom Prometheus collectors to OTEL + wire into startup #4 / E1)
• OTEL metrics on admin listener (see Add {request_errors, answer} to Gx/Ro/Rf/NASREQ #7 / E4)
• /health + /ready on 9464 (replace /status/ready on 8000)
• structured JSON logging to stdout
• rename release smf-c-node -> smf
• converge YAML config to generate-ahead (escript -> sys.config)
• k8s manifests (StatefulSet + headless Service + ConfigMap + probes)
• bin/smf cluster/drain CLI