chore: proxy image preview in frontend (#11957)

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

- **New Features**
	- Images and icons in bookmark cards are now loaded through an image proxy for improved reliability and consistency.
	- Embed blocks for GitHub, Loom, and YouTube now display banner and creator images via an image proxy service for enhanced image loading.

- **Refactor**
	- Simplified backend URL handling and proxy logic for images, resulting in more efficient processing and reduced complexity.
	- Consolidated image proxy middleware and services into a shared adapter module for streamlined imports and improved maintainability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/shared/src/adapters/middlewares/index.ts

@@ -3,6 +3,7 @@ export * from './copy';
 export * from './doc-link';
 export * from './file-name';
 export * from './paste';
+export * from './proxy';
 export * from './replace-id';
 export * from './surface-ref-to-embed';
 export * from './title';

blocksuite/affine/shared/src/adapters/middlewares/proxy.ts

@@ -0,0 +1,53 @@
+import type { TransformerMiddleware } from '@blocksuite/store';
+import { StoreExtension } from '@blocksuite/store';
+
+import { DEFAULT_IMAGE_PROXY_ENDPOINT } from '../../consts';
+
+export const customImageProxyMiddleware = (
+  imageProxyURL: string
+): TransformerMiddleware => {
+  return ({ adapterConfigs }) => {
+    adapterConfigs.set('imageProxy', imageProxyURL);
+  };
+};
+
+const imageProxyMiddlewareBuilder = () => {
+  let middleware = customImageProxyMiddleware(DEFAULT_IMAGE_PROXY_ENDPOINT);
+  return {
+    get: () => middleware,
+    set: (url: string) => {
+      middleware = customImageProxyMiddleware(url);
+    },
+  };
+};
+
+const defaultImageProxyMiddlewarBuilder = imageProxyMiddlewareBuilder();
+
+export const setImageProxyMiddlewareURL = defaultImageProxyMiddlewarBuilder.set;
+
+export const defaultImageProxyMiddleware =
+  defaultImageProxyMiddlewarBuilder.get();
+
+// TODO(@mirone): this should be configured when setup instead of runtime
+export class ImageProxyService extends StoreExtension {
+  static override key = 'image-proxy';
+
+  private _imageProxyURL = DEFAULT_IMAGE_PROXY_ENDPOINT;
+
+  setImageProxyURL(url: string) {
+    this._imageProxyURL = url;
+    setImageProxyMiddlewareURL(url);
+  }
+
+  buildUrl(imageUrl: string) {
+    if (imageUrl.startsWith(this.imageProxyURL)) {
+      return imageUrl;
+    }
+
+    return `${this.imageProxyURL}?url=${encodeURIComponent(imageUrl)}`;
+  }
+
+  get imageProxyURL() {
+    return this._imageProxyURL;
+  }
+}