2D elements: plane stress, plane strain and axisymmetric sections on the DOF framework; mesh.planar (M4) (#39)

Model: planar section kinds with Extent, element edges in sets, edge-weighted 2D loads,
centrifugal load, 2D model checks. fem: Plane kernels on Basis::{Tri3,Tri6,Quad4,Quad8}
declaring ElementDofs::new(DofSet::PLANE); QM6 incompatible modes with the
Wilson-Ibrahimbegovic correction. Solver: Kernel enum on the DofLayout; 3D results
bit-identical (hash-checked). Decks: Abaqus CPS/CPE/CAX, Nastran membranes and RFORCE,
LS-DYNA ELFORM 12/13. Mesh: free triangle mesher, planar region meshing, face boundaries.
Engine: mesh.planar with tagged edges. Analytic verification suite in solver/tests/plane.rs.


Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/lib.rs

@@ -330,6 +330,13 @@ mod tests {
             json!({"surface": -1}),
             json!({"surface": 1e300}),
             json!({"surface": "0", "weld": -1, "feature_angle": 1e300}),
+            json!({"polygon": vec![[0.0, 0.0]; 200_000], "size": 1}),
+            json!({"polygon": [[0, 0], [1e308, 0], [0, 1e308]], "size": 1e-300}),
+            json!({"polygon": [[0, 0], [1, 0], [0, 1]], "holes": vec![[[0.1, 0.1], [0.2, 0.1], [0.1, 0.2]]; 20_000], "size": 0.5}),
+            json!({"polygon": [[0, 0], [1, 0], [0, 1]], "holes": [[[0.1, 0.1], [0.2, 0.1], [0.1, 0.2]], [[0.1, 0.1], [0.2, 0.1], [0.1, 0.2]]], "size": 0.2}),
+            json!({"polygon": [["a", 0], [1, null], {}], "size": "big", "kind": 7}),
+            json!({"polygon": [[0, 0], [1, 0], [0, 1]], "size": 1e300, "kind": "tri6", "max_elements": 1e300}),
+            json!({"body": "Body1", "face": "", "tolerance": 0.05, "size": 1}),
             // Model definitions.
             json!({"name": "x".repeat(100_000)}),
             json!({"name": "A\u{0}"}),
@@ -345,6 +352,12 @@ mod tests {
             json!({"name": "A", "set": "all", "material": "Steel", "kind": {"type": "beam", "profile": {"type": "pipe", "radius": 1, "thickness": 2}, "orientation": [0, 0, 0]}}),
             json!({"name": "A", "set": "all", "material": "Steel", "kind": {"type": "shell", "thickness": 1e308, "offset": -0.5, "points": 4294967295u64}}),
             json!({"name": "A", "xyz": [1e308, 0, 0]}),
+            json!({"name": "A", "set": "all", "material": "Steel", "kind": {"type": "plane_stress", "thickness": -1}}),
+            json!({"name": "A", "set": "all", "material": "Steel", "kind": {"type": "plane_strain", "thickness": 1e308}}),
+            json!({"name": "A", "set": "all", "material": "Steel", "kind": {"type": "axisymmetric", "axis": "x"}}),
+            json!({"name": "A", "type": "centrifugal", "angular_velocity": 1e300, "point": [0, 0, 0], "axis": [0, 1, 0]}),
+            json!({"name": "A", "type": "centrifugal", "angular_velocity": 1, "point": [0, 0, 0], "axis": [0, 0, 0]}),
+            json!({"name": "A", "edges": [{"element": u32::MAX, "edge": 0}]}),
             json!({"name": "A", "reference_point": "RP", "set": "end", "kind": "rigid", "dofs": [0, 7]}),
             json!({"name": "A", "type": "fixed", "target": {"set": "nope"}}),
             json!({"name": "A", "type": "displacement", "target": {"reference_point": "RP"}, "values": [null, null, null, null, null, null]}),