The whisper-server runner's model_id is inherited from the gguf MODEL config's
alias, which links the two. So:
- Adding a model config creates one runner whose id is the config's alias
  (auto-minted + stamped onto the config when no alias is given).
- Removing a config (by config_id or by path) tears down the runner whose id
  matches that config's alias — one config removed = one runner removed/killed.

Replaces the interim model_config_id link.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>