Audit the 17 pre-existing mapped kinds; add shared basic-geometry validation

Runs every first-generation kind through the real-runner lifecycle driver.
The audit found Ellipse unvalidated, zero-height Text/MText and non-finite
Arc angles and Point/Line thickness accepted, and no creation-time checks
for most kinds. validate_basic_entity now covers them and refuses only
problems an edit introduces. Twelve kinds pass every gate; Polyline,
Polyline2D, Polyline3D and Spline carry pinned persistence findings, and
Insert is update-only.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/plugin-host-model-completion-plan.md

@@ -9,7 +9,7 @@ As of 20 September 2026, the working branch is `plugin/host-model-api` at
 [#1391](https://github.com/HakanSeven12/OpenCADStudio/pull/1391). Host API is
 v7. The Python feature has explicit writes for **37 of 43** canvas kinds: 36
 are creatable and `Insert` remains update-only. This is **not** 37 completed
-kinds: Tolerance, Shape, AttributeEntity, Hatch, MLine, Dimension, MultiLeader, Table, PolygonMesh, PolyfaceMesh, Mesh and Wipeout pass every completion gate.
+kinds: Tolerance, Shape, AttributeEntity, Hatch, MLine, Dimension, MultiLeader, Table, PolygonMesh, PolyfaceMesh, Mesh, Wipeout, Point, Line, Circle, Arc, Ellipse, LwPolyline, Text, MText, Ray, XLine, Solid and Face3D pass every completion gate; the audited Polyline, Polyline2D, Polyline3D, Spline and Insert pass every gate that their format or update-only status allows.
 AttributeDefinition passes its host and real IPC lifecycle but remains short of
 `Complete` because the previously pinned CAD codec dropped optional ATTDEF
 fields during DXF reads; revalidate that blocker against the current
@@ -171,3 +171,4 @@ exact queue above and update statuses with evidence after each increment.
 - Mapped `ViewBorder` with viewport and scale reference rules. All gates pass in DWG; DXF loading does not restore the typed entity (pinned by a canary). The queue now continues with `SectionSymbol`.
 - Recorded `SectionSymbol` (queue item 15) as **blocked**: it needs a section view style and view representation the host cannot create, and its raw point-count fields have no documented derivation. Mapped `Light` (item 16); every gate passes except DXF `cast_shadows`, which the reader drops (pinned by a canary). The queue now continues with `Region`.
 - Recorded `Region`, `Body`, `Solid3D`, `Surface` (queue items 17-20) and `Ole2Frame` (item 21) as **blocked**. The ACIS kinds need a host-side kernel-backed create/transform API that regenerates the payload, wires and silhouettes; the OLE frame needs a valid embedded-storage fixture. No opaque payload is rewritten. With this the ordered queue is complete: 12 kinds are fully complete, Leader, Helix, Underlay, ViewBorder and Light are mapped but blocked at DWG/DXF persistence by acadrust gaps, RasterImage and Viewport lack an oracle or linkage, and six kinds are blocked. Next work is the engine fixes behind the canary assertions, the mapped-kind audit of the 17 pre-existing kinds, and merging `origin/main`.
+- Audited the 17 pre-existing mapped kinds through the shared real-runner driver (`audit_python_*`). The audit found and fixed genuine validation gaps: Ellipse had none, Text and MText accepted a zero height, Arc accepted non-finite angles, Point and Line accepted infinite thickness, and most basic kinds had no creation-time validation. A shared `validate_basic_entity` now covers Point, Line, Circle, Arc, Ellipse, Text, MText, LwPolyline, Polyline, Polyline2D, Polyline3D and Spline, refusing only problems an edit introduces so already-invalid legacy values stay editable. Twelve of the 17 kinds now pass every gate (Point, Line, Circle, Arc, Ellipse, LwPolyline, Text, MText, Ray, XLine, Solid, Face3D). Four expose persistence findings pinned by canaries (Polyline reopens as Polyline3D; Polyline2D reopens as LwPolyline in DXF; Polyline3D loses elevation in DWG; Spline loses weights in DXF), and Insert is update-only with all applicable gates passing. The driver gained per-format DWG expectations and a host-made block fixture for Insert.