feat: improve editor performance (#14429)

#### PR Dependency Tree


* **PR #14429** 👈

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**
* HTML import now splits lines on <br> into separate paragraphs while
preserving inline formatting.

* **Bug Fixes**
* Paste falls back to inserting after the first paragraph when no
explicit target is found.

* **Style**
  * Improved page-mode viewport styling for consistent content layout.

* **Tests**
* Added snapshot tests for <br>-based paragraph splitting; re-enabled an
e2e drag-page test.

* **Chores**
* Deferred/deduplicated font loading, inline text caching,
drag-handle/pointer optimizations, and safer inline render
synchronization.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/integration-test/src/__tests__/edgeless/frame.spec.ts

@@ -47,7 +47,10 @@ describe('frame', () => {
     expect(rect!.width).toBeGreaterThan(0);
     expect(rect!.height).toBeGreaterThan(0);
 
-    const [titleX, titleY] = service.viewport.toModelCoord(rect!.x, rect!.y);
+    const [titleX, titleY] = service.viewport.toModelCoordFromClientCoord([
+      rect!.x,
+      rect!.y,
+    ]);
     expect(titleX).toBeCloseTo(0);
     expect(titleY).toBeLessThan(0);
 
@@ -66,10 +69,11 @@ describe('frame', () => {
     if (!nestedTitle) return;
 
     const nestedTitleRect = nestedTitle.getBoundingClientRect()!;
-    const [nestedTitleX, nestedTitleY] = service.viewport.toModelCoord(
-      nestedTitleRect.x,
-      nestedTitleRect.y
-    );
+    const [nestedTitleX, nestedTitleY] =
+      service.viewport.toModelCoordFromClientCoord([
+        nestedTitleRect.x,
+        nestedTitleRect.y,
+      ]);
 
     expect(nestedTitleX).toBeGreaterThan(20);
     expect(nestedTitleY).toBeGreaterThan(20);