chore(editor): change edgeless-text default color to black (#12361)

Closes: [BS-3506](https://linear.app/affine-design/issue/BS-3506/edgeless-text-默认改为黑色)

### Dark
<img width="691" alt="Screenshot 2025-05-19 at 19 32 52" src="https://github.com/user-attachments/assets/2927d13b-0300-4293-8f8f-7891fd87a680" />

### Light
<img width="639" alt="Screenshot 2025-05-19 at 19 33 05" src="https://github.com/user-attachments/assets/4429f6f9-b374-4b17-87f4-ae09204f1538" />

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

## Summary by CodeRabbit

- **New Features**
  - Improved edgeless text block styling to support theme-based color, font, and alignment settings.

- **Style**
  - Updated the default text color in edgeless text blocks to black, with support for separate dark and light mode colors.

- **Bug Fixes**
  - Ensured the color picker and block rendering reflect the updated default color.

- **Tests**
  - Adjusted tests and snapshots to expect the new default color and theme-based color structure.

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

blocksuite/affine/blocks/edgeless-text/src/edgeless-text-block.ts

@@ -26,6 +26,7 @@ import {
   GfxViewInteractionExtension,
   type SelectedContext,
 } from '@blocksuite/std/gfx';
+import { computed } from '@preact/signals-core';
 import { css, html } from 'lit';
 import { query, state } from 'lit/decorators.js';
 import { type StyleInfo, styleMap } from 'lit/directives/style-map.js';
@@ -82,6 +83,23 @@ export class EdgelessTextBlockComponent extends GfxBlockComponent<EdgelessTextBl
     });
   }
 
+  private readonly _style$ = computed(() => {
+    const {
+      color$: { value: color },
+      fontFamily$: { value: fontFamily },
+      fontStyle$: { value: fontStyle },
+      fontWeight$: { value: fontWeight },
+      textAlign$: { value: textAlign },
+    } = this.model.props;
+    return {
+      color,
+      fontFamily,
+      fontStyle,
+      fontWeight,
+      textAlign,
+    };
+  });
+
   checkWidthOverflow(width: number) {
     let wValid = true;
 
@@ -365,7 +383,7 @@ export class EdgelessTextBlockComponent extends GfxBlockComponent<EdgelessTextBl
 
   override renderPageContent() {
     const { color, fontFamily, fontStyle, fontWeight, textAlign } =
-      this.model.props;
+      this._style$.value;
     const themeProvider = this.std.get(ThemeProvider);
     const textColor = themeProvider.generateColorProperty(
       color,