feat(core): embedding progress (#12367)

### TL;DR

feat: show embedding progress in settings panel

![截屏2025-05-19 20.25.19.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/MyktQ6Qwc7H6TiRCFoYN/59d8f9ef-0876-4ed5-9c09-db12686adb47.png)

### What changed

* show embedding progress in settings panel
* polling embedding status based on RxJS

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

- **New Features**
  - Added real-time embedding progress tracking and display in embedding settings, including a visual progress bar and status messages.
  - Introduced localized text for embedding progress statuses.
  - Added an optional test ID attribute to the progress bar component for improved testing.
- **Style**
  - Added new styles for embedding progress UI elements.
- **Tests**
  - Added an end-to-end test to verify embedding progress is displayed correctly in the settings UI.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -6215,6 +6215,22 @@ export function useAFFiNEI18N(): {
       * `AI can call files embedded in the workspace.`
       */
     ["com.affine.settings.workspace.indexer-embedding.embedding.switch.description"](): string;
+    /**
+      * `Embedding progress`
+      */
+    ["com.affine.settings.workspace.indexer-embedding.embedding.progress.title"](): string;
+    /**
+      * `Syncing`
+      */
+    ["com.affine.settings.workspace.indexer-embedding.embedding.progress.syncing"](): string;
+    /**
+      * `Synced`
+      */
+    ["com.affine.settings.workspace.indexer-embedding.embedding.progress.synced"](): string;
+    /**
+      * `Loading sync status...`
+      */
+    ["com.affine.settings.workspace.indexer-embedding.embedding.progress.loading-sync-status"](): string;
     /**
       * `Ignore Docs`
       */

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

@@ -1553,6 +1553,10 @@
   "com.affine.settings.workspace.indexer-embedding.embedding.select-doc": "Select doc",
   "com.affine.settings.workspace.indexer-embedding.embedding.switch.title": "Workspace Embedding",
   "com.affine.settings.workspace.indexer-embedding.embedding.switch.description": "AI can call files embedded in the workspace.",
+  "com.affine.settings.workspace.indexer-embedding.embedding.progress.title": "Embedding progress",
+  "com.affine.settings.workspace.indexer-embedding.embedding.progress.syncing": "Syncing",
+  "com.affine.settings.workspace.indexer-embedding.embedding.progress.synced": "Synced",
+  "com.affine.settings.workspace.indexer-embedding.embedding.progress.loading-sync-status": "Loading sync status...",
   "com.affine.settings.workspace.indexer-embedding.embedding.ignore-docs.title": "Ignore Docs",
   "com.affine.settings.workspace.indexer-embedding.embedding.ignore-docs.description": "The Ignored docs will not be embedded into the current workspace.",
   "com.affine.settings.workspace.indexer-embedding.embedding.additional-attachments.title": "Additional attachments",