feat: opstool-style scene recipe for the Plotly canvas

Frames the view deterministically: Scene now carries padded per-axis bounds
(opstool's pad_ratio 0.15, with unit slack on degenerate axes) plus
axis_overrides() pinning range + autorange=False, so the model is never
flush against the viewport edge. Adds entity hover templates (Node #n /
Element #n with an empty extra tag), and an optional axis outline (grid +
ticks) - off by default so the SAP2000-like clean viewport is unchanged;
the coloured X/Y/Z axis lines always stay as the orientation cue.

The outline is exposed as a bool in the Plot Properties table, so the
table-driven dialog now builds a checkbox for kind=bool.

tests/unit/test_plotly_trace_builder.py

@@ -206,3 +206,57 @@ def test_frame_trace_meta_marks_elements_pickable() -> None:
     # None separators break the line into per-element segments.
     assert None in frames["x"]
     assert len(frames["customdata"]) == len(frames["x"])
+
+
+# ── scene recipe (opstool-derived framing) ───────────────────────────────
+def test_axis_bounds_are_padded_around_the_model() -> None:
+    project = _load("cantilever")
+    scene = PlotlyTraceBuilder().build(project, SceneOptions())
+    points = np.array([node.coords for node in project.nodes], dtype=float)
+    for index, axis in enumerate(("x", "y", "z")):
+        low, high = scene.axis_bounds[axis]
+        assert low < points[:, index].min() or low <= points[:, index].min()
+        assert high > points[:, index].max() or high >= points[:, index].max()
+    assert scene.diagonal > 0
+
+
+def test_planar_model_gets_unit_slack_on_the_flat_axis() -> None:
+    project = _load("basic_truss")
+    scene = PlotlyTraceBuilder().build(project, SceneOptions())
+    low, high = scene.axis_bounds["z"]
+    assert high - low > 0  # a degenerate axis must not collapse the view
+
+
+def test_axis_overrides_pin_ranges_with_autorange_off() -> None:
+    scene = PlotlyTraceBuilder().build(_load("cantilever"), SceneOptions())
+    overrides = scene.axis_overrides()
+    assert set(overrides) == {"xaxis", "yaxis", "zaxis"}
+    for axis, override in overrides.items():
+        assert override["autorange"] is False
+        assert len(override["range"]) == 2
+        assert override["range"] == list(scene.axis_bounds[axis[0]])
+
+
+def test_hover_templates_identify_entities() -> None:
+    scene = PlotlyTraceBuilder().build(_load("basic_truss"), SceneOptions())
+    (nodes,) = _traces(scene, "nodes")
+    (frames,) = _traces(scene, "elements")
+    assert nodes["hovertemplate"] == "Node #%{customdata}<extra></extra>"
+    assert frames["hovertemplate"] == "Element #%{customdata}<extra></extra>"
+    # Hover must not fall back to the raw-id "skip" mode.
+    assert "hoverinfo" not in nodes
+
+
+def test_axis_outline_flag_toggles_grid_and_ticks() -> None:
+    plain = RenderStyle()
+    outlined = RenderStyle(show_axis_outline=True)
+    project = _load("cantilever")
+    scene_plain = PlotlyTraceBuilder(plain).build(project, SceneOptions())
+    scene_outlined = PlotlyTraceBuilder(outlined).build(project, SceneOptions())
+
+    off_axis = scene_plain.layout["scene"]["xaxis"]
+    on_axis = scene_outlined.layout["scene"]["xaxis"]
+    assert off_axis["showgrid"] is False and off_axis["showticklabels"] is False
+    assert on_axis["showgrid"] is True and on_axis["showticklabels"] is True
+    # The coloured axis lines stay visible either way (orientation cue).
+    assert off_axis["visible"] is True and on_axis["visible"] is True

tests/unit/test_render_style.py

@@ -49,7 +49,7 @@ def test_editable_subset_matches_the_field_table() -> None:
     kinds = {name: kind for name, _label, kind in STYLE_FIELDS}
     for name in EDITABLE_FIELDS:
         assert hasattr(style, name), name
-        assert kinds[name] in {"color", "float", "int"}
+        assert kinds[name] in {"color", "float", "int", "bool"}
 
 
 def test_response_colorscale_is_an_evenly_spaced_mapping() -> None: