Fixes the "only radeon was stopped while everything under throttle" case and gives
colibri a clean pause instead of SIGSTOP.

Thermal (engine_supervisor):
- Per-engine CPU gating: measure each engine's process-group CPU (rolling max) and
  apply the GLOBAL cpu_hot/cpu_warm term ONLY to real CPU-heat sources. A GPU-bound
  engine (embeddings) is never paused/stranded in the resume<CPU<high dead-band that
  a CPU-heavy engine (colibri) keeps the shared CPU parked in.
- Targeted SIGSTOP: _thermal_signal now freezes the engine's native compute CHILDREN
  (colibri/ds4/whisper-server), leaving the Python HTTP server alive to ack
  pause/resume — killing the resume-fail / SIGSTOP↔SIGCONT thrash. Falls back to
  killpg for in-process (torch) engines.

colibri graceful PAUSE/RESUME:
- packaging/patch-colibri.py: idempotent serve-mux patch adding PAUSE/RESUME control
  frames — colibri idles the decode loop between tokens (keeping KV) instead of being
  frozen; build.sh applies it after clone.
- MuxEngine.pause()/resume() + colibri_worker.pause_all()/resume_all(); the engine's
  /internal/thermal-pause|-resume now drives them, so the cooperative thermal throttle
  can cool the box without SIGSTOP.

Credits (requested): clear acknowledgements for the brilliant engines coderai builds
on — colibri (JustVugg), ds4/DwarfStar (antirez), llama.cpp/whisper.cpp (Gerganov),
and VPR/geo research — in the admin settings UI, README, and docs (new
docs/glm-colibri.md, ds4 doc footer).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LoSpEthysqmseCc6Geizty