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/ui/style/plotstyle.rs

@@ -92,11 +92,11 @@ fn field_style(theme: &Theme, status: text_input::Status) -> text_input::Style {
 /// unit-tested and benched without building widgets. `pub` (not
 /// `pub(crate)`) so the `cargo bench` harness (`benches/`, an external
 /// crate) can measure it as `ui_plotstyle_layer_usage`.
-pub fn build_layer_usage(document: &acadrust::CadDocument) -> Vec<Vec<String>> {
+pub fn build_layer_usage(document: &codec::CadDocument) -> Vec<Vec<String>> {
     let mut layer_usage = vec![Vec::<String>::new(); 256];
 
     for layer in document.layers.iter() {
-        if let acadrust::types::Color::Index(aci) = &layer.color {
+        if let codec::types::Color::Index(aci) = &layer.color {
             let index = *aci as usize;
 
             if index > 0 && index < layer_usage.len() {
@@ -114,7 +114,7 @@ pub fn build_layer_usage(document: &acadrust::CadDocument) -> Vec<Vec<String>> {
 }
 
 pub fn view_window<'a>(
-    document: &'a acadrust::CadDocument,
+    document: &'a codec::CadDocument,
     table: Option<&'a crate::io::plot_style::PlotStyleTable>,
     selected_aci: u8,
     color_buf: &'a str,
@@ -182,7 +182,7 @@ pub fn view_window<'a>(
                 String::new()
             };
             let (aci_color, _) = crate::ui::properties::acad_color_display(
-                acadrust::types::Color::Index(aci),
+                codec::types::Color::Index(aci),
             );
             let has_override = table
                 .and_then(|t| t.aci_entries.get(aci as usize))
@@ -379,14 +379,14 @@ pub fn view_window<'a>(
                     .strip_prefix('#')
                     .filter(|hex| hex.len() == 6)
                     .and_then(|hex| u32::from_str_radix(hex, 16).ok())
-                    .map(|rgb| acadrust::types::Color::Rgb {
+                    .map(|rgb| codec::types::Color::Rgb {
                         r: ((rgb >> 16) & 0xFF) as u8,
                         g: ((rgb >> 8) & 0xFF) as u8,
                         b: (rgb & 0xFF) as u8,
                     });
 
                 let display_color = selected_color
-                    .unwrap_or(acadrust::types::Color::Index(selected_aci));
+                    .unwrap_or(codec::types::Color::Index(selected_aci));
 
                 let (swatch_color, _) =
                     crate::ui::properties::acad_color_display(display_color);
@@ -559,19 +559,19 @@ mod layer_usage_tests {
     use super::*;
 
     fn indexed_layer(
-        doc: &mut acadrust::CadDocument,
+        doc: &mut codec::CadDocument,
         name: &str,
         aci: u8,
-    ) -> acadrust::tables::Layer {
-        let mut layer = acadrust::tables::Layer::new(name);
+    ) -> codec::tables::Layer {
+        let mut layer = codec::tables::Layer::new(name);
         layer.handle = doc.allocate_handle();
-        layer.color = acadrust::types::Color::Index(aci);
+        layer.color = codec::types::Color::Index(aci);
         layer
     }
 
     #[test]
     fn build_layer_usage_buckets_index_colors() {
-        let mut doc = acadrust::CadDocument::new();
+        let mut doc = codec::CadDocument::new();
         let a = indexed_layer(&mut doc, "WALLS", 1);
         let b = indexed_layer(&mut doc, "doors", 1);
         let c = indexed_layer(&mut doc, "ROOF", 3);
@@ -589,10 +589,10 @@ mod layer_usage_tests {
 
     #[test]
     fn build_layer_usage_ignores_non_index_colors() {
-        let mut doc = acadrust::CadDocument::new();
-        let mut truecolor = acadrust::tables::Layer::new("TRUECOLOR");
+        let mut doc = codec::CadDocument::new();
+        let mut truecolor = codec::tables::Layer::new("TRUECOLOR");
         truecolor.handle = doc.allocate_handle();
-        truecolor.color = acadrust::types::Color::Rgb {
+        truecolor.color = codec::types::Color::Rgb {
             r: 10,
             g: 20,
             b: 30,