feat(core): migrate more pull to realtime (#14936)

#### PR Dependency Tree


* **PR #14936** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

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## Summary by CodeRabbit

* **Refactor**
* Consolidated realtime subscription patterns for consistent, more
reliable live updates across comments, notifications, transcription
tasks, and embedding progress.
* Standardized realtime room naming and subscription keys for
deterministic delivery.

* **New Features**
* Introduced a reusable live-query mechanism powering realtime snapshot
+ event workflows used by comments, notifications, transcript tasks, and
embedding progress.

* **Tests**
* Added tests covering live-query behavior and deterministic
subscription key generation.

[![Review Change
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tests/affine-cloud-copilot/e2e/settings/embedding.spec.ts

@@ -127,10 +127,8 @@ test.describe('AISettings/Embedding', () => {
     await page.getByTestId('embedding-progress-wrapper');
 
     const progress = await page.getByTestId('embedding-progress');
-    // wait for the progress to be loading
     const title = await page.getByTestId('embedding-progress-title');
-    await expect(title).toHaveText(/Loading sync status/i);
-    await expect(progress).not.toBeVisible();
+    await expect(title).not.toHaveAttribute('data-progress', 'loading');
 
     const count = await page.getByTestId('embedding-progress-count');
     await expect(count).toHaveText(/\d+\/\d+/);