Import CAD projects and cad-router v1

SimpleCADAPI/docs/api/SemanticRef.md

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+# SemanticRef
+
+## Class Definition
+
+```python
+class SemanticRef(graph_id: str, node_id: str, entity_type: str, entity_id: str)
+```
+
+*Source: topology.py*
+
+## Import Surface
+
+- top-level: `from simplecadapi import SemanticRef`
+
+## Description
+
+Stable reference to a semantic model entity in the recorded graph.