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/entities/light.rs

@@ -1,7 +1,7 @@
 //! Light entity display glyph (point / spot / distant).
 //!
 //! Lights are nonprint helper entities: the DWG reader decodes the source
-//! position and aim point (see `acadrust`'s `Light`); here we synthesize a
+//! position and aim point (see `opencadcodec`'s `Light`); here we synthesize a
 //! wireframe glyph so the light is visible and selectable in the editor, the
 //! same way AutoCAD shows a light symbol.
 //!
@@ -9,8 +9,8 @@
 //! zoom) via [`relative_render`], falling back to a small fixed world size when
 //! no world-per-pixel factor is available (e.g. snapshot tessellation).
 
-use acadrust::entities::Light;
-use acadrust::EntityType;
+use codec::entities::Light;
+use codec::EntityType;
 use crate::t;
 
 use crate::command::EntityTransform;
@@ -190,7 +190,7 @@ fn build(l: &Light, r: f64) -> RenderEntity {
 /// available (the caller then falls back to the fixed-world [`to_render`]).
 pub fn relative_render(
     entity: &EntityType,
-    _document: &acadrust::CadDocument,
+    _document: &codec::CadDocument,
     wpp: Option<f32>,
 ) -> Option<RenderEntity> {
     let EntityType::Light(l) = entity else {
@@ -201,7 +201,7 @@ pub fn relative_render(
 }
 
 impl RenderConvertible for Light {
-    fn to_render(&self, _document: &acadrust::CadDocument) -> Option<RenderEntity> {
+    fn to_render(&self, _document: &codec::CadDocument) -> Option<RenderEntity> {
         Some(build(self, FIXED_WORLD))
     }
 }