mohdel v0.106.0

Added

• OpenAI-compatible adapter for xiaomi/* models (reasoning_content,
  image input, tool calling).
• mistral creator entry (fixes a dangling reference from
  providers.js). Adapter and provider config were already present.
• CallEnvelope.idleHeartbeatMs (optional) — when set, the session
  emits a synthetic {type:'idle', sinceMs} event whenever the
  adapter has been silent for at least that many milliseconds, and
  re-emits every idleHeartbeatMs while the silence persists. The
  timer resets on every real event.
• Event::Idle variant on the wire (JS + Rust). Advisory only —
  mohdel never aborts on its own. Consumers decide whether to log,
  bump a watchdog, or trigger an external cancel. Omitting
  idleHeartbeatMs disables the feature and preserves the prior
  event stream byte-for-byte.
• Conformance fixtures: new idle event in
  test/conformance/events.json; full-options envelope gains
  idleHeartbeatMs.