fix(export_gltf): update for Blender 5.0 API (wm.stl_import, shade_smooth_by_angle)

- bpy.ops.import_mesh.stl → bpy.ops.wm.stl_import (removed in Blender 4.0)
- mesh.use_auto_smooth = True → bpy.ops.object.shade_smooth_by_angle()
  (use_auto_smooth removed in Blender 4.1)
- Apply smooth shading to all objects unconditionally after scale, so
  GLB is smooth-shaded even when no sharp edge midpoints are present

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

render-worker/scripts/export_gltf.py

@@ -48,12 +48,19 @@ def mark_sharp_edges_by_proximity(midpoints_mm: list, threshold_mm: float = 1.0)
         return
 
     import bpy  # type: ignore[import]
+    import math
 
     for obj in bpy.data.objects:
         if obj.type != "MESH":
             continue
         mesh = obj.data
-        mesh.use_auto_smooth = True
+        # Blender 4.1+ removed use_auto_smooth — use shade_smooth_by_angle instead
+        bpy.context.view_layer.objects.active = obj
+        obj.select_set(True)
+        try:
+            bpy.ops.object.shade_smooth_by_angle(angle=math.radians(30))
+        except Exception:
+            pass  # fallback: stay flat-shaded
         mw = obj.matrix_world
         for edge in mesh.edges:
             v1 = mw @ mesh.vertices[edge.vertices[0]].co
@@ -81,8 +88,8 @@ def main() -> None:
     # Clean scene
     bpy.ops.wm.read_factory_settings(use_empty=True)
 
-    # Import STL
+    # Import STL (bpy.ops.wm.stl_import is the Blender 4.0+ API)
-    bpy.ops.import_mesh.stl(filepath=args.stl_path)
+    bpy.ops.wm.stl_import(filepath=args.stl_path)
 
     # Scale mm → m
     for obj in bpy.context.selected_objects:
@@ -90,6 +97,17 @@ def main() -> None:
         bpy.context.view_layer.objects.active = obj
         bpy.ops.object.transform_apply(scale=True)
 
+    # Apply smooth shading with 30° angle threshold (Blender 4.1+ API)
+    import math as _math
+    for obj in bpy.data.objects:
+        if obj.type == "MESH":
+            bpy.context.view_layer.objects.active = obj
+            obj.select_set(True)
+            try:
+                bpy.ops.object.shade_smooth_by_angle(angle=_math.radians(30))
+            except Exception:
+                pass
+
     # Mark sharp edges for better UV seams
     if sharp_edge_midpoints:
         mark_sharp_edges_by_proximity(sharp_edge_midpoints)