feat(core): support collection search for ai chat (#10987)

Close [BS-2787](https://linear.app/affine-design/issue/BS-2787).
Close [BS-2788](https://linear.app/affine-design/issue/BS-2788).

![截屏2025-03-19 14.15.54.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/sJGviKxfE3Ap685cl5bj/573450f9-791b-4cd9-9c75-df93bf9966b4.png)

packages/frontend/i18n/src/i18n.gen.ts

@@ -6833,6 +6833,10 @@ export function useAFFiNEI18N(): {
       * `Tags`
       */
     ["com.affine.editor.at-menu.tags"](): string;
+    /**
+      * `Collections`
+      */
+    ["com.affine.editor.at-menu.collections"](): string;
     /**
       * `Loading...`
       */

packages/frontend/i18n/src/resources/en.json

@@ -1698,6 +1698,7 @@
   "com.affine.editor.at-menu.link-to-doc": "Search for \"{{query}}\"",
   "com.affine.editor.at-menu.recent-docs": "Recent",
   "com.affine.editor.at-menu.tags": "Tags",
+  "com.affine.editor.at-menu.collections": "Collections",
   "com.affine.editor.at-menu.loading": "Loading...",
   "com.affine.editor.at-menu.new-doc": "New",
   "com.affine.editor.at-menu.create-page": "New \"{{name}}\" page",