Bind libslic3r's TriangleMesh directly with a shared_ptr holder rather than
wrapping it in a HostTriangleMesh snapshot struct. ModelVolume.mesh() hands
out the volume's own shared_ptr (via const_pointer_cast, which only serves
the holder type), so the Python object pins the snapshot exactly as the
wrapper did, and the zero-copy views now use the Python object as their
array base — deleting the capsule machinery.
The wrapper's type-level constness becomes a documented rule instead:
handed-out meshes are copy-on-write snapshots shared across threads, so the
binding exposes only const methods; a future mutable-mesh API must operate
on plugin-owned copies handed back via ModelVolume::set_mesh.
No Python-visible change (orca.host.TriangleMesh, same methods/docstrings),
and plugins now hold the real class a future set_mesh() will accept.
Verified with slic3rutils and fff_print suites.
PluginHostApi.cpp had grown into one TU holding the module entry point plus
three unrelated domains (presets, model/mesh graph, app access), and
PluginHostSlicing.cpp mixed ownable geometry value types with the
non-owning live print graph. Reorganize the orca.host surface into
plugin/host/ with one registrar per domain:
- PluginHost.hpp/.cpp entry point (replaces PluginHostApi)
- PluginHostBindings.hpp internal per-domain registrar declarations
- PluginHostGeometry.cpp BoundingBox, Point, Polygon, ExPolygon + ndarray parsing
- PluginHostMesh.hpp/.cpp TriangleMesh snapshot (own TU ahead of planned
mesh construct/mutate APIs)
- PluginHostPresets.cpp Preset, PresetCollection, PresetBundle
- PluginHostModel.cpp scene graph: Model, ModelObject, ModelInstance, ModelVolume
- PluginHostApp.cpp Plater + plater()/model()/preset_bundle() accessors
- PluginHostSlicing.cpp live print graph only, now with a single lifetime story
- PluginHostUi.hpp/.cpp moved unchanged
PluginBindingUtils.hpp stays at plugin/ root: it is shared with pluginTypes/
and tests, not host/-specific.
No Python-visible change: same submodules, class names and docstrings.
Verified with slic3rutils and fff_print suites.
