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 <[email protected]>

src/modules/draw/modify/block_edit.rs

@@ -15,7 +15,7 @@
 // block record in place, so there is no copy-back and no transform — the space
 // render filter (`current_layout_block_handle`) already draws only the block.
 
-use acadrust::{EntityType, Handle};
+use codec::{EntityType, Handle};
 use glam::DVec3;
 
 use crate::command::{CadCommand, CmdResult};
@@ -66,7 +66,7 @@ pub struct BlockEditSession {
     /// Rebasing the origin moves them with the definition; Discard restores
     /// their exact on-entry state.
     pub reference_attributes:
-        Vec<(Handle, Vec<acadrust::entities::AttributeEntity>)>,
+        Vec<(Handle, Vec<codec::entities::AttributeEntity>)>,
     /// Camera state of the space that was active when BEDIT began, restored
     /// on Save/Discard so the view returns exactly where it was (#425).
     pub return_camera: crate::scene::view::camera::Camera,
@@ -75,7 +75,7 @@ pub struct BlockEditSession {
     pub editor_camera: crate::scene::view::camera::Camera,
     /// Transient UCS being manipulated in this block tab. On commit its full
     /// frame is baked into the definition and this returns to `None`.
-    pub editor_ucs: Option<acadrust::tables::Ucs>,
+    pub editor_ucs: Option<codec::tables::Ucs>,
 }
 
 // ── BEDIT pick command ─────────────────────────────────────────────────────