feat(editor): add experimental feature citation (#11984)

Closes: [BS-3122](https://linear.app/affine-design/issue/BS-3122/footnote-definition-adapter-适配)
Closes: [BS-3123](https://linear.app/affine-design/issue/BS-3123/几个-block-card-view-适配-footnote-态)

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

- **New Features**
  - Introduced a new citation card component and web element for displaying citations.
  - Added support for citation-style rendering in attachment, bookmark, and linked document blocks.
  - Enabled citation parsing from footnote definitions in markdown for attachments, bookmarks, and linked docs.
  - Added a feature flag to enable or disable citation features.
  - Provided new toolbar logic to disable downloads for citation-style attachments.

- **Improvements**
  - Updated block models and properties to support citation identifiers.
  - Added localization and settings for the citation experimental feature.
  - Enhanced markdown adapters to recognize and process citation footnotes.
  - Included new constants and styles for citation card display.

- **Bug Fixes**
  - Ensured readonly state is respected in block interactions and rendering for citation blocks.

- **Documentation**
  - Added exports and effects for new citation components and features.

- **Tests**
  - Updated snapshots to include citation-related properties in block data.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/blocks/embed/src/embed-linked-doc-block/adapters/markdown.ts

@@ -1,16 +1,91 @@
-import { EmbedLinkedDocBlockSchema } from '@blocksuite/affine-model';
+import {
+  EmbedLinkedDocBlockSchema,
+  FootNoteReferenceParamsSchema,
+} from '@blocksuite/affine-model';
 import {
   AdapterTextUtils,
   BlockMarkdownAdapterExtension,
   type BlockMarkdownAdapterMatcher,
+  FOOTNOTE_DEFINITION_PREFIX,
+  getFootnoteDefinitionText,
+  isFootnoteDefinitionNode,
+  type MarkdownAST,
 } from '@blocksuite/affine-shared/adapters';
+import { FeatureFlagService } from '@blocksuite/affine-shared/services';
+import { nanoid } from '@blocksuite/store';
+
+const isLinkedDocFootnoteDefinitionNode = (node: MarkdownAST) => {
+  if (!isFootnoteDefinitionNode(node)) return false;
+  const footnoteDefinition = getFootnoteDefinitionText(node);
+  try {
+    const footnoteDefinitionJson = FootNoteReferenceParamsSchema.parse(
+      JSON.parse(footnoteDefinition)
+    );
+    return (
+      footnoteDefinitionJson.type === 'doc' && !!footnoteDefinitionJson.docId
+    );
+  } catch {
+    return false;
+  }
+};
 
 export const embedLinkedDocBlockMarkdownAdapterMatcher: BlockMarkdownAdapterMatcher =
   {
     flavour: EmbedLinkedDocBlockSchema.model.flavour,
-    toMatch: () => false,
+    toMatch: o => isLinkedDocFootnoteDefinitionNode(o.node),
     fromMatch: o => o.node.flavour === EmbedLinkedDocBlockSchema.model.flavour,
-    toBlockSnapshot: {},
+    toBlockSnapshot: {
+      enter: (o, context) => {
+        const { provider } = context;
+        let enableCitation = false;
+        try {
+          const featureFlagService = provider?.get(FeatureFlagService);
+          enableCitation = !!featureFlagService?.getFlag('enable_citation');
+        } catch {
+          enableCitation = false;
+        }
+        if (!isFootnoteDefinitionNode(o.node) || !enableCitation) {
+          return;
+        }
+
+        const { walkerContext, configs } = context;
+        const footnoteIdentifier = o.node.identifier;
+        const footnoteDefinitionKey = `${FOOTNOTE_DEFINITION_PREFIX}${footnoteIdentifier}`;
+        const footnoteDefinition = configs.get(footnoteDefinitionKey);
+        if (!footnoteDefinition) {
+          return;
+        }
+        try {
+          const footnoteDefinitionJson = FootNoteReferenceParamsSchema.parse(
+            JSON.parse(footnoteDefinition)
+          );
+          const { docId } = footnoteDefinitionJson;
+          if (!docId) {
+            return;
+          }
+          walkerContext
+            .openNode(
+              {
+                type: 'block',
+                id: nanoid(),
+                flavour: EmbedLinkedDocBlockSchema.model.flavour,
+                props: {
+                  pageId: docId,
+                  footnoteIdentifier,
+                  style: 'citation',
+                },
+                children: [],
+              },
+              'children'
+            )
+            .closeNode();
+          walkerContext.skipAllChildren();
+        } catch (err) {
+          console.warn('Failed to parse linked doc footnote definition:', err);
+          return;
+        }
+      },
+    },
     fromBlockSnapshot: {
       enter: (o, context) => {
         const { configs, walkerContext } = context;