feat: improve grouping perf in edgeless (#14442)

fix #14433 

#### PR Dependency Tree


* **PR #14442** 👈

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**
  * Level-of-detail thumbnails for large images.
  * Adaptive pacing for snapping, distribution and other alignment work.
  * RAF coalescer utility to batch high-frequency updates.
  * Operation timing utility to measure synchronous work.

* **Improvements**
* Batch group/ungroup reparenting that preserves element order and
selection.
  * Coalesced panning and drag updates to reduce jitter.
* Connector/group indexing for more reliable updates, deletions and
sync.
  * Throttled viewport refresh behavior.

* **Documentation**
  * Docs added for RAF coalescer and measureOperation.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/gfx/pointer/src/snap/adaptive-load-controller.ts

@@ -0,0 +1,65 @@
+export class AdaptiveStrideController {
+  private _stride = 1;
+
+  private _ticks = 0;
+
+  constructor(
+    private readonly _options: {
+      heavyCostMs: number;
+      maxStride: number;
+      recoveryCostMs: number;
+    }
+  ) {}
+
+  reportCost(costMs: number) {
+    if (costMs > this._options.heavyCostMs) {
+      this._stride = Math.min(this._options.maxStride, this._stride + 1);
+      return;
+    }
+
+    if (costMs < this._options.recoveryCostMs && this._stride > 1) {
+      this._stride -= 1;
+    }
+  }
+
+  reset() {
+    this._stride = 1;
+    this._ticks = 0;
+  }
+
+  shouldSkip() {
+    const shouldSkip = this._stride > 1 && this._ticks % this._stride !== 0;
+    this._ticks += 1;
+    return shouldSkip;
+  }
+}
+
+export class AdaptiveCooldownController {
+  private _remainingFrames = 0;
+
+  constructor(
+    private readonly _options: {
+      cooldownFrames: number;
+      maxCostMs: number;
+    }
+  ) {}
+
+  reportCost(costMs: number) {
+    if (costMs > this._options.maxCostMs) {
+      this._remainingFrames = this._options.cooldownFrames;
+    }
+  }
+
+  reset() {
+    this._remainingFrames = 0;
+  }
+
+  shouldRun() {
+    if (this._remainingFrames <= 0) {
+      return true;
+    }
+
+    this._remainingFrames -= 1;
+    return false;
+  }
+}