Follow-ups after merging the out-of-process plugin isolation work:
- Convert the out-of-process interactive adapter's `on_point` /
`on_entity_pick` to `glam::DVec3`, matching the `CadCommand` trait,
which moved to f64 pick coordinates. The branch predated that change
and no longer compiled against the trait.
- Contain plugin constructor panics in `export_plugin!`: the constructor
runs across the C ABI boundary in `ocs_plugin_register`, where an
unwinding panic is undefined behavior. Catch it and return null, which
the loader already treats as a failed registration.
- Reap killed runner processes. The spawn-timeout and disconnect paths
called `child.kill()` without `wait()`, leaving a zombie on Unix until
the host exited. Route both — and `shutdown()` — through a shared
`reap()` that kills and waits on a detached thread.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>