perf(editor): fallback to placeholder for canvas text (#12033)

### TL;DR

For canvas elements, this PR adds placeholders during zooming operations to improve performance.

![image.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/lEGcysB4lFTEbCwZ8jMv/8c8daea8-1eb4-419b-a4f4-2a8847f40b7b.png)

### What changed?

- Implemented placeholder rendering during zooming operations in the canvas renderer, but not only DOM.
- Added a `forceFullRender` property to the `GfxCompatibleInterface` to allow elements to opt out of placeholder rendering
- Set `forceFullRender = true` for connectors to ensure they always render properly, even during zooming
- Connected the turbo renderer to the viewport's zooming state to automatically switch between full and placeholder rendering

### Why make this change?

Rendering complex elements during zooming operations can cause performance issues and make the UI feel sluggish. Rendering connector label also leads to high cost DOM `set font` delays.

![image.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/lEGcysB4lFTEbCwZ8jMv/961fb847-24b4-4a7f-b9dc-21b0a5edaaa1.png)

The turbo renderer improves performance by displaying simple placeholders for elements during zooming, while still rendering critical elements like connectors fully. This creates a smoother user experience while maintaining essential visual information.

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

## Summary by CodeRabbit

- **New Features**
  - Introduced a feature-flag-controlled "turbo" rendering mode that displays placeholder graphics during zooming for improved performance.
  - Added the ability to override placeholder rendering for specific elements, ensuring full rendering when required.

- **Bug Fixes**
  - Enhanced rendering logic to ensure connectors always render fully, even during zoom operations.

- **Documentation**
  - Updated API documentation to reflect new properties related to rendering behavior.

- **Tests**
  - Improved tests to verify correct rendering behavior for connectors.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/gfx/connector/src/element-renderer/index.ts

@@ -249,13 +249,20 @@ function renderLabel(
   const [, , w, h] = labelXYWH!;
   const cx = w / 2;
   const cy = h / 2;
+
+  ctx.setTransform(matrix);
+
+  if (renderer.usePlaceholder) {
+    ctx.fillStyle = 'rgba(200, 200, 200, 0.5)';
+    ctx.fillRect(0, 0, w, h);
+    return; // Skip actual label rendering
+  }
+
   const deltas = wrapTextDeltas(text!, font, w);
   const lines = deltaInsertsToChunks(deltas);
   const lineHeight = getLineHeight(fontFamily, fontSize, fontWeight);
   const textHeight = (lines.length - 1) * lineHeight * 0.5;
 
-  ctx.setTransform(matrix);
-
   ctx.font = font;
   ctx.textAlign = textAlign;
   ctx.textBaseline = 'middle';