oracle: filleted L-bracket on the octree all-hex mesh

A slow theory case: the corpus bracket meshed by mesh.hex.octree at 7, 5 and 4 mm, clamped
at the base and loaded by 2 kN. Checks equilibrium, that every element is certified valid,
the mesh volume against the CAD volume, the beam bending stress of the upright leg
(sigma = M c / I = 145.3 MPa, within 5%) and the convergence of the fillet von Mises stress
against the 4 mm mesh.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

tests/oracle/octree-filleted-bracket/design.json

@@ -0,0 +1,89 @@
+{
+ "commands": [
+  {
+   "command": "sketch.create",
+   "params": {
+    "plane": "XY",
+    "name": "Profile"
+   }
+  },
+  {
+   "command": "sketch.line",
+   "params": {
+    "points": [
+     [
+      0,
+      0
+     ],
+     [
+      60,
+      0
+     ],
+     [
+      60,
+      8
+     ],
+     [
+      8,
+      8
+     ],
+     [
+      8,
+      50
+     ],
+     [
+      0,
+      50
+     ]
+    ],
+    "closed": true
+   }
+  },
+  {
+   "command": "sketch.finish",
+   "params": {}
+  },
+  {
+   "command": "solid.extrude",
+   "params": {
+    "distance": 40,
+    "body_name": "Bracket"
+   }
+  },
+  {
+   "command": "solid.fillet",
+   "params": {
+    "edges": [
+     [
+      8,
+      8,
+      20
+     ]
+    ],
+    "radius": 6
+   }
+  },
+  {
+   "command": "solid.hole",
+   "params": {
+    "position": [
+     40,
+     8,
+     20
+    ],
+    "diameter": 8
+   }
+  },
+  {
+   "command": "solid.hole",
+   "params": {
+    "position": [
+     8,
+     32,
+     20
+    ],
+    "diameter": 8
+   }
+  }
+ ]
+}