[borodino] fix(sliver): C2 callback pipeline + implant generation workaround

Commit `cd6cc76`

sliver-entrypoint: resolve LHOST from C2_REDIRECTORS (37.16.12.4), start MTLS listener :8888, workaround sliver v1.7.3 runc/cgroup vendoring bug via fallback copy from build dir + async wait + delete stale bin/ before generate
stack: C2_REDIRECTORS env, port 8888 mode ingress, sliver-implants volume in worker
redirector: nginx stream TCP proxy :8888→sliver-server via VPN (SLIVER_VPN_IP), inotify-tools + stream module, fly.toml port 8888

Co-Authored-By: Claude Sonnet 4.6 noreply@anthropic.com