Binding compatibility

cargo xtask api-coverage also writes docs/compatibility/api-bindings.md: every public member of a Unity type Tassix has, checked by the signature compiled code binds to (declaring type or a base, name, generic arity, parameter and return types, static or instance; fields as fields). Members Tassix lacks altogether stay on the coverage page. Against Unity 6000.3: 20,229 signatures, 1,393 didn't bind, sorted by cause.
Fixed: 262 overloads that optional parameters stood in for (Physics and Physics2D queries above all, GetComponent(s)InChildren/InParent, Animator, Rigidbody, Debug.DrawRay...), 162 in overloads Unity 6000.3 adds beside the by-value ones on its math types, 12 fields and properties swapped (LoadSceneParameters, CreateSceneParameters and MeshLodRange properties; ButtonControl.pressPoint and ColorBlock.defaultColorBlock fields), 49 missing setters (Input System controls' and devices' protected and public setters, DeltaControl's directions as AxisControls), InputActionMap(). The overloads were written by the tool's --fix-bindings mode: it finds each method's source through its PDB and adds Unity's signatures beside it, forwarding with the defaults written there (C# keeps source calls on the same methods).
The fixture plugin (apps/mcp/tests/fixtures/plugin) is now built against Unity 6000.3's modules and calls a sample of the fixed signatures; the e2e test checks the results.
Left: 11 public setters that need behavior (Camera.projectionMatrix and worldToCameraMatrix, Renderer.bounds, Mesh.lodCount, Texture.dimension...), and 893 overloads Tassix doesn't have (missing API rather than mismatched; listed on the page).