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]>

docs/plugin-host-review-guide.md

@@ -126,8 +126,8 @@ several kinds and features are interleaved, so read by area rather than commit b
 ## What is deliberately not done
 
 - **Twelve of the 43 kinds are not `Complete`** (see the ledger). Seven are blocked by DXF bugs in
-  cadcodec, whose fixes are submitted as [cadcodec#48](https://github.com/HakanSeven12/cadcodec/pull/48) and
-  [#51](https://github.com/HakanSeven12/cadcodec/pull/51). **This change still pins the unfixed cadcodec revision**,
+  opencadcodec, whose fixes are submitted as [opencadcodec#48](https://github.com/HakanSeven12/opencadcodec/pull/48) and
+  [#51](https://github.com/HakanSeven12/opencadcodec/pull/51). **This change still pins the unfixed opencadcodec revision**,
   so its canary tests assert the old behaviour; once those merge, the pin moves, the canaries flip and those kinds
   can be marked complete. The other five are held by the DWG format, a kind change on DXF save, an image-reactor
   structure that cannot be verified, an update-only decision, and a missing creation path.