fix(editor): prevent SwiftKey IME double input (#13590)

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[BS-3610](https://linear.app/affine-design/issue/BS-3610/bug-每次按空格会出现重复单词-，特定输入法，比如swiftkey)

#### PR Dependency Tree

* **PR #13591**
  * **PR #13590** 👈

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

- Bug Fixes
- Android: More reliable Backspace/delete handling, preventing missed
inputs and double-deletions.
- Android: Cursor/selection is correctly restored after merging a
paragraph with the previous block.
- Android: Smoother IME composition input; captures correct composition
range.
- Deletion across lines and around embeds/empty lines is more
consistent.
- Chores
- Internal event handling updated to improve Android compatibility and
stability (no user-facing changes).
<!-- end of auto-generated comment: release notes by coderabbit.ai -->





#### PR Dependency Tree


* **PR #13591**
  * **PR #13590** 👈

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

blocksuite/framework/std/src/event/control/keyboard.ts

@@ -1,4 +1,5 @@
-import { IS_MAC } from '@blocksuite/global/env';
+import { DisposableGroup } from '@blocksuite/global/disposable';
+import { IS_ANDROID, IS_MAC } from '@blocksuite/global/env';
 
 import {
   type UIEventHandler,
@@ -6,7 +7,7 @@ import {
   UIEventStateContext,
 } from '../base.js';
 import type { EventOptions, UIEventDispatcher } from '../dispatcher.js';
-import { bindKeymap } from '../keymap.js';
+import { androidBindKeymapPatch, bindKeymap } from '../keymap.js';
 import { KeyboardEventState } from '../state/index.js';
 import { EventScopeSourceType, EventSourceState } from '../state/source.js';
 
@@ -87,15 +88,29 @@ export class KeyboardControl {
   }
 
   bindHotkey(keymap: Record<string, UIEventHandler>, options?: EventOptions) {
-    return this._dispatcher.add(
-      'keyDown',
-      ctx => {
-        if (this.composition) return false;
-        const binding = bindKeymap(keymap);
-        return binding(ctx);
-      },
-      options
+    const disposables = new DisposableGroup();
+    if (IS_ANDROID) {
+      disposables.add(
+        this._dispatcher.add('beforeInput', ctx => {
+          if (this.composition) return false;
+          const binding = androidBindKeymapPatch(keymap);
+          return binding(ctx);
+        })
+      );
+    }
+
+    disposables.add(
+      this._dispatcher.add(
+        'keyDown',
+        ctx => {
+          if (this.composition) return false;
+          const binding = bindKeymap(keymap);
+          return binding(ctx);
+        },
+        options
+      )
     );
+    return () => disposables.dispose();
   }
 
   listen() {

blocksuite/framework/std/src/event/keymap.ts

@@ -103,3 +103,25 @@ export function bindKeymap(
     return false;
   };
 }
+
+// In some IME of Android like, the keypress event  dose not contain
+// the information about what key is pressed. See
+// https://stackoverflow.com/a/68188679
+// https://stackoverflow.com/a/66724830
+export function androidBindKeymapPatch(
+  bindings: Record<string, UIEventHandler>
+): UIEventHandler {
+  return ctx => {
+    const event = ctx.get('defaultState').event;
+    if (!(event instanceof InputEvent)) return;
+
+    if (
+      event.inputType === 'deleteContentBackward' &&
+      'Backspace' in bindings
+    ) {
+      return bindings['Backspace'](ctx);
+    }
+
+    return false;
+  };
+}