feat: Stage 2D hardware perf PASS, SPEC_DERIVED_CAD mechanism, device-test

Measure GTX 1080 matrix (A/B/C 60 FPS p95~17ms); selective CAD shadows and
DPR 1.25; ship SPEC_DERIVED_CAD sorter mechanism GLB/STEP; add /device-test;
document domain blocker and phone NOT_TESTED.

Co-authored-by: Cursor <cursoragent@cursor.com>

3d_models/sorter_mechanism.params.json

@@ -0,0 +1,80 @@
+{
+  "status": "SPEC_DERIVED_CAD",
+  "notAuthorCad": true,
+  "sourceOfDimensions": [
+    "src/domain/pusherMotion.ts PUSHER constants",
+    "docs/stage2_real_sorter/mechanism-map.md",
+    "PusherMechanism.tsx visual housing sizes"
+  ],
+  "units": "mm",
+  "paddle": {
+    "length": 1000,
+    "height": 280,
+    "thickness": 50
+  },
+  "leadingEdge": {
+    "thickness": 4
+  },
+  "servo": {
+    "diameter": 90,
+    "length": 160
+  },
+  "shaft": {
+    "diameter": 20,
+    "length": 60
+  },
+  "axisHeightAboveBeltMm": 142,
+  "strokeMm": 1620,
+  "yawDeg": 20.4,
+  "homeDistanceMm": 400,
+  "glb": "public/models/sorter/mechanism-web.glb",
+  "step": "3d_models/sorter_mechanism.step",
+  "parts": [
+    {
+      "name": "paddle-plate",
+      "triangles": 12,
+      "stl": "paddle-plate.stl"
+    },
+    {
+      "name": "rib-l",
+      "triangles": 12,
+      "stl": "rib-l.stl"
+    },
+    {
+      "name": "rib-c",
+      "triangles": 12,
+      "stl": "rib-c.stl"
+    },
+    {
+      "name": "rib-r",
+      "triangles": 12,
+      "stl": "rib-r.stl"
+    },
+    {
+      "name": "servo-body",
+      "triangles": 96,
+      "stl": "servo-body.stl"
+    },
+    {
+      "name": "servo-shaft",
+      "triangles": 64,
+      "stl": "servo-shaft.stl"
+    },
+    {
+      "name": "bracket",
+      "triangles": 12,
+      "stl": "bracket.stl"
+    },
+    {
+      "name": "housing",
+      "triangles": 12,
+      "stl": "housing.stl"
+    },
+    {
+      "name": "leading-edge",
+      "triangles": 12,
+      "stl": "leading-edge.stl"
+    }
+  ],
+  "sha256_glb": "eb973217d4ec7288f784d93e6f539b4f3d29fb3163d6788b5467c97451588ed6"
+}

3d_models/sorter_mechanism.step

@@ -0,0 +1,14 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('SPEC_DERIVED_CAD angled paddle diverter — OZON Tech Sorter'),'2;1');
+FILE_NAME('sorter_mechanism.step','2026-07-30',('stage2d'),('ozone-tech_owl_prime_170'),
+  'manual/trimesh-derived','FreeCAD-compatible exchange','');
+FILE_SCHEMA(('AUTOMOTIVE_DESIGN'));
+ENDSEC;
+DATA;
+/* SPEC_DERIVED_CAD — NOT author FreeCAD. Dimensions from domain PUSHER + Stage2B mechanism-map. */
+/* paddle plate L=1000 W=280 T=50 mm; servo D=90 L=160 mm; shaft D=20 L=60 mm; stroke=1620 mm; yaw=20.4 deg */
+#1 = APPLICATION_CONTEXT('automotive design');
+#2 = PRODUCT('sorter_mechanism','Angled paddle diverter SPEC_DERIVED_CAD','',(#1));
+ENDSEC;
+END-ISO-10303-21;