feat: node graph overlay; move to opencadcodec/opencadkernel/opencadgraph

The codec and kernel repositories and crates are renamed opencadcodec and
opencadkernel. Inside OCS they are depended on under short keys, so code
reads `codec::`, `kernel::` and the new `graph::` (opencadgraph, the node
graph engine). File-format and protocol spellings stay as they were: the
ACIS product id `acadrust`, the ACADRUST_* switches and the plugin
version keys `acadrust_version` / `acadrust_source`.

A button left of MCP on the command line opens a translucent node graph
over the viewport, with a palette of object, input, math, logic, list,
text and geometry nodes added by click or drag. An object node owns
drawing entities and its rows are the Properties panel's own rows for
them: the single-object page is extracted from refresh_properties as
entity_property_sections, values use the control protocol's
property_json, and writes go through set_property_value with a property
target override, so the panel, MCP and the graph share one read/write
path. A list reaching an object row makes one entity per element. Each
graph action is one undo step; the canvas pans and zooms.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/modules/draw/modify/spline_ops.rs

@@ -1,6 +1,6 @@
 // Shared B-spline utilities for modify commands (TRIM, BREAK, OFFSET, LENGTHEN).
 //
-// The evaluation lives in cadkernel; this file converts a drawing's SPLINE
+// The evaluation lives in opencadkernel; this file converts a drawing's SPLINE
 // entity to and from it and keeps the knot-domain call shapes the commands
 // were written against.
 //
@@ -9,11 +9,11 @@
 // piece of a NURBS circle into a piece of a parabola — a change that looks
 // fine until it is measured.
 
-use acadrust::entities::Spline;
-use acadrust::types::Vector3;
-use acadrust::Handle;
-use cadkernel::geom2d::{NurbsCurve, Parameterization};
-use cadkernel::space::Plane;
+use codec::entities::Spline;
+use codec::types::Vector3;
+use codec::Handle;
+use kernel::geom2d::{NurbsCurve, Parameterization};
+use kernel::space::Plane;
 
 /// The drawing plane a spline sits on.
 ///
@@ -30,7 +30,7 @@ fn elevation(spl: &Spline) -> f64 {
 
 // ── Conversion ─────────────────────────────────────────────────────────────
 
-/// Convert an acadrust `Spline` to a kernel `NurbsCurve`, weights included.
+/// Convert an opencadcodec `Spline` to a kernel `NurbsCurve`, weights included.
 ///
 /// A SPLINE is stored one of two ways and both turn up: a control polygon the
 /// curve approaches, or fit points it must pass through with optional end
@@ -114,7 +114,7 @@ fn spline_to_nurbs_with(
     )
 }
 
-/// Rebuild an acadrust `Spline` from a kernel curve.
+/// Rebuild an opencadcodec `Spline` from a kernel curve.
 ///
 /// The `template` supplies entity common data and the Z elevation; splines
 /// here are planar, so the kernel's 2D points are lifted back onto it.