fix: Generate faces for sketch objects and fix tool preview state

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

src/ViewportWidget.cpp

@@ -730,6 +730,7 @@ void ViewportWidget::drawSketch(const SketchFeature* sketch)
             m_litShaderProgram->setAttributeBuffer(1, GL_FLOAT, 3 * sizeof(GLfloat), 3, 6 * sizeof(GLfloat));
 
             glDrawArrays(GL_TRIANGLES, 0, faceData.size() / 6);
+            m_litShaderProgram->disableAttributeArray(1);
             m_shaderProgram->bind(); // rebind simple shader for subsequent draws
         }
         glEnable(GL_CULL_FACE);