wgpu: overlay points (sprite-style, quad-expanded with stroke halo)

Ports GL OverlayRenderer's setOverlayPoints API to WgpuOverlayRenderer.
Each point becomes a 6-vertex screen-space quad sized to inner_diameter
+ 2*stroke_extra; the fragment reads its per-vertex corner varying
instead of gl_PointCoord (WebGPU has no sized-point primitive). Sharp
inner/stroke transition + AA on the outer edge only, matching GL.

Single uniform slot per set — colors are global to the call, not per
point. Vertex buffer regrows 1.5× on demand so steady-state sets don't
re-allocate.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ifcviewer-wgpu/WgpuViewportWindow.h

@@ -284,8 +284,14 @@ private:
 
     // Overlay primitives. Mirror GL ViewportWindow so the Measurement +
     // dimension tools can target either backend through one API.
-    // Empty groups clears the current set.
+    // Empty inputs clears the corresponding set.
     void  setOverlayLines(const std::vector<WgpuOverlayRenderer::LineGroup>& groups);
+    void  setOverlayPoints(const std::vector<float>& world_xyz,
+                           float r, float g, float b, float a,
+                           float pixel_size,
+                           float stroke_r, float stroke_g,
+                           float stroke_b, float stroke_a,
+                           float stroke_extra);
 
     void  ensureHizTextures(int viewport_w, int viewport_h);
     void  releaseHizResources();