fix(editor): should preserve format in <p> when importing html (#12275)

Closes: [BS-3485](https://linear.app/affine-design/issue/BS-3485/粘贴-html-格式的内容时，紧邻着-bold-text-的普通文本会丢失空格)

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

- **Bug Fixes**
  - Improved handling of spaces and whitespace in paragraphs when converting HTML with inline formatting, ensuring spaces are preserved as in the original content.

- **Tests**
  - Added a new test to verify that spaces are correctly preserved in paragraphs containing bold and italic formatting during HTML conversion.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/all/src/__tests__/adapters/html.unit.spec.ts

@@ -2360,6 +2360,65 @@ describe('html to snapshot', () => {
     expect(nanoidReplacement(rawBlockSnapshot)).toEqual(blockSnapshot);
   });
 
+  test('should preserve space in p', async () => {
+    const html = template(
+      `<p>A <b>bold text</b> followed by a <i>italic text</i></p>`
+    );
+
+    const blockSnapshot: BlockSnapshot = {
+      type: 'block',
+      id: 'matchesReplaceMap[0]',
+      flavour: 'affine:note',
+      props: {
+        xywh: '[0,0,800,95]',
+        background: DefaultTheme.noteBackgrounColor,
+        index: 'a0',
+        hidden: false,
+        displayMode: NoteDisplayMode.DocAndEdgeless,
+      },
+      children: [
+        {
+          type: 'block',
+          id: 'matchesReplaceMap[1]',
+          flavour: 'affine:paragraph',
+          props: {
+            type: 'text',
+            text: {
+              '$blocksuite:internal:text$': true,
+              delta: [
+                {
+                  insert: 'A ',
+                },
+                {
+                  insert: 'bold text',
+                  attributes: {
+                    bold: true,
+                  },
+                },
+                {
+                  insert: ' followed by a ',
+                },
+                {
+                  insert: 'italic text',
+                  attributes: {
+                    italic: true,
+                  },
+                },
+              ],
+            },
+          },
+          children: [],
+        },
+      ],
+    };
+
+    const htmlAdapter = new HtmlAdapter(createJob(), provider);
+    const rawBlockSnapshot = await htmlAdapter.toBlockSnapshot({
+      file: html,
+    });
+    expect(nanoidReplacement(rawBlockSnapshot)).toEqual(blockSnapshot);
+  });
+
   test('span nested in p', async () => {
     const html = template(
       `<p><span>aaa</span><span>bbb</span><span>ccc</span></p>`

blocksuite/affine/inlines/preset/src/adapters/html/html-inline.ts

@@ -5,6 +5,24 @@ import {
 import { collapseWhiteSpace } from 'collapse-white-space';
 import type { Element } from 'hast';
 
+/**
+ * Handle empty text nodes created by HTML parser for styling purposes.
+ * These nodes typically contain only whitespace/newlines, for example:
+ * ```json
+ * {
+ *   "type": "text",
+ *   "value": "\n\n  \n  \n  "
+ * }
+ * ```
+ * We collapse and trim the whitespace to check if the node is truly empty,
+ * and return an empty array in that case.
+ */
+const isEmptyText = (ast: HtmlAST): boolean => {
+  return (
+    ast.type === 'text' && collapseWhiteSpace(ast.value, { trim: true }) === ''
+  );
+};
+
 const isElement = (ast: HtmlAST): ast is Element => {
   return ast.type === 'element';
 };
@@ -22,12 +40,16 @@ export const htmlTextToDeltaMatcher = HtmlASTToDeltaExtension({
       return [];
     }
     const { options } = context;
-    options.trim ??= true;
+    options.trim ??= false;
 
     if (options.pre) {
       return [{ insert: ast.value }];
     }
 
+    if (isEmptyText(ast)) {
+      return [];
+    }
+
     const value = options.trim
       ? collapseWhiteSpace(ast.value, { trim: options.trim })
       : collapseWhiteSpace(ast.value);