feat: integrate SimpleCADAPI 2.0.2 CAD workflows

SimpleCADAPI/docs/api/model.md

@@ -0,0 +1,50 @@
+# model
+
+## API Definition
+
+```python
+def model(
+    func=None,
+    *,
+    graph_id: Optional[str] = None,
+    export_dir: Optional[str | Path] = None,
+) -> Callable
+```
+
+*Source: graph.py*
+
+## Import Surface
+
+- top-level: `from simplecadapi import model`
+
+## Description
+
+Decorate the single top-level entry point of a replayable model. Each invocation
+creates and owns exactly one `GraphSession`, activates it while the function
+runs, captures model/session JSON in memory, and returns a `ModelResult`. When
+`export_dir` is provided, explicitly captured geometry/product values produce
+one `<graph_id>.scene.zip` in that directory. The package embeds
+`model/model.json`, mapped project-relative Python source files under
+`sources/`, and the GLB/entity assets required for rendering and selection. It
+does not create adjacent model/session JSON, STEP, STL, or FCStd files.
+
+```python
+import simplecadapi as scad
+
+@scad.model(graph_id="bracket")
+def build_bracket():
+    body = scad.make_box_rsolid(width=20.0, height=10.0, depth=3.0)
+    scad.capture_result(value=body)
+    return body
+
+result = build_bracket()
+print(result.result_node_ids)
+```
+
+Use `result.artifact_paths["scene"]` to locate the package, or call
+`result.export_artifacts(output_dir=...)` after a model has run without an
+export directory. The explicit `export_dir` opt-in avoids unexpected filesystem
+writes for library callers and tests.
+
+Do not nest `@model` functions or create another `GraphSession` inside a model
+function. Use `@requires_session` for child builders.