feat: add test tube pick task with custom assets and grasp annotations

- Add pick_test_tube task: USDC asset repackaging, grasp generation, task config
- Add tools: usdc_to_obj.py, repackage_test_tube.py, fix_test_tube_materials.py
- Add custom_task_guide.md: full Chinese documentation for creating custom tasks
- Add crawled InternDataEngine online docs (23 pages)
- Add grasp generation script (gen_tube_grasp.py) and pipeline config

migrate/usdc_to_obj.py

@@ -0,0 +1,64 @@
+"""
+Extract mesh from USD/USDC and export as OBJ file.
+
+Usage:
+    python migrate/usdc_to_obj.py --input path/to/file.usdc --output path/to/output/
+"""
+import argparse
+import os
+import numpy as np
+from pxr import Usd, UsdGeom
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--input", required=True)
+    parser.add_argument("--output", default=".")
+    args = parser.parse_args()
+
+    os.makedirs(args.output, exist_ok=True)
+    obj_path = os.path.join(args.output, "Aligned_obj.obj")
+
+    stage = Usd.Stage.Open(args.input)
+    vert_offset = 0
+
+    with open(obj_path, "w") as f:
+        f.write("# Exported from USD\n\n")
+
+        for prim in stage.Traverse():
+            if prim.GetTypeName() != "Mesh":
+                continue
+
+            mesh = UsdGeom.Mesh(prim)
+            points = mesh.GetPointsAttr().Get()
+            if not points:
+                continue
+
+            face_counts = mesh.GetFaceVertexCountsAttr().Get()
+            face_indices = mesh.GetFaceVertexIndicesAttr().Get()
+
+            name = str(prim.GetPath()).replace("/", "_").strip("_")
+            f.write(f"o {name}\n")
+            print(f"  Mesh: {prim.GetPath()} ({len(points)} verts)")
+
+            for p in points:
+                f.write(f"v {p[0]:.8f} {p[1]:.8f} {p[2]:.8f}\n")
+
+            if face_counts and face_indices:
+                idx = 0
+                for fc in face_counts:
+                    verts = []
+                    for j in range(fc):
+                        verts.append(face_indices[idx] + 1 + vert_offset)
+                        idx += 1
+                    # Triangulate: fan from first vertex
+                    for j in range(1, len(verts) - 1):
+                        f.write(f"f {verts[0]} {verts[j]} {verts[j+1]}\n")
+
+            vert_offset += len(points)
+
+    print(f"\nSaved: {obj_path} ({vert_offset} total vertices)")
+
+
+if __name__ == "__main__":
+    main()