mesh-compile: planar faces still triangulated with earcut (same T-junction failure as #253)

[GeneralPawz]

Found while fixing #253. In axiolid-construct, earcut produced a triangulation with the correct total area but a T-junction: an edge ran straight past a hole's corner. Extruded meshes were then open, and an area check can't detect it. #253 replaced earcut in construct with a certified ear clipper (exact `orient2d` decisions, plus an edge-parity certificate that refuses by name).

`axiolid-mesh-compile` still uses earcut for planar faces, in `planar.rs` (authored polygon faces, including the #254 warped-face path) and in `brep.rs` (planar B-rep faces with holes). The same T-junction can open those meshes.

Done when

• mesh-compile's planar triangulation uses the certified clipper from construct: profile triangulation leaves an open mesh for two holes side by side #253 (shared through the dependency rule, or moved to a common crate if needed) or applies the same edge-parity certificate.
• Faces with several holes in one band compile to closed meshes.
• The property tests from construct: profile triangulation leaves an open mesh for two holes side by side #253 run through the mesh-compile paths.
• earcut is removed from the workspace, or its remaining uses are certified.

[GeneralPawz]

Released in axiolid-construct 0.3.15, axiolid-evaluate 0.3.6, axiolid-reference 0.3.7, axiolid-mesh-compile 0.3.14 (9877cdc).