feat(editor): improve edgeless perf & memory usage (#14591)

#### PR Dependency Tree


* **PR #14591** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* New canvas renderer debug metrics and controls for runtime inspection.
* Mindmap/group reordering now normalizes group targets, improving
reorder consistency.

* **Bug Fixes**
  * Fixed connector behavior for empty/degenerate paths.
* More aggressive viewport invalidation so structural changes display
correctly.
* Improved z-index synchronization during transforms and layer updates.

* **Performance**
* Retained DOM caching for brushes, shapes, and connectors to reduce DOM
churn.
* Targeted canvas refreshes, pooling, and reuse to lower redraw and
memory overhead.

* **Tests**
* Added canvas renderer performance benchmarks and curve edge-case unit
tests.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/framework/global/src/__tests__/curve.unit.spec.ts

@@ -0,0 +1,22 @@
+import { describe, expect, test } from 'vitest';
+
+import { getBezierParameters } from '../gfx/curve.js';
+import { PointLocation } from '../gfx/model/index.js';
+
+describe('getBezierParameters', () => {
+  test('should handle empty path', () => {
+    expect(() => getBezierParameters([])).not.toThrow();
+    expect(getBezierParameters([])).toEqual([
+      new PointLocation(),
+      new PointLocation(),
+      new PointLocation(),
+      new PointLocation(),
+    ]);
+  });
+
+  test('should handle single-point path', () => {
+    const point = new PointLocation([10, 20]);
+
+    expect(getBezierParameters([point])).toEqual([point, point, point, point]);
+  });
+});

blocksuite/framework/global/src/gfx/curve.ts

@@ -142,6 +142,11 @@ export function getBezierNearestPoint(
 export function getBezierParameters(
   points: PointLocation[]
 ): BezierCurveParameters {
+  if (points.length === 0) {
+    const point = new PointLocation();
+    return [point, point, point, point];
+  }
+
   // Fallback for degenerate Bezier curve (all points are at the same position)
   if (points.length === 1) {
     const point = points[0];