feat(server): realtime notification & task status (#14934)

#### PR Dependency Tree


* **PR #14934** 👈

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

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

* **New Features**
* Full realtime platform added: live notifications, comments, embedding
progress, and transcription task updates via realtime subscriptions.

* **Chores**
* Frontend switched from polling/GraphQL queries to realtime channels;
legacy query fields marked deprecated and client libs updated to use
realtime APIs.

[![Review Change
Stack](https://storage.googleapis.com/coderabbit_public_assets/review-stack-in-coderabbit-ui.svg)](https://app.coderabbit.ai/change-stack/toeverything/AFFiNE/pull/14934)
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#### PR Dependency Tree


* **PR #14934** 👈
  * **PR #14936**

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

tools/utils/src/workspace.gen.ts

@@ -1111,6 +1111,7 @@ export const PackageList = [
       'tools/cli',
       'tools/utils',
       'packages/common/graphql',
+      'packages/common/realtime',
     ],
   },
   {
@@ -1148,6 +1149,7 @@ export const PackageList = [
     name: '@affine/nbstore',
     workspaceDependencies: [
       'packages/common/reader',
+      'packages/common/realtime',
       'packages/common/infra',
       'packages/common/error',
       'packages/common/graphql',
@@ -1159,6 +1161,11 @@ export const PackageList = [
     name: '@affine/reader',
     workspaceDependencies: ['blocksuite/affine/all'],
   },
+  {
+    location: 'packages/common/realtime',
+    name: '@affine/realtime',
+    workspaceDependencies: ['packages/common/graphql'],
+  },
   {
     location: 'packages/common/s3-compat',
     name: '@affine/s3-compat',
@@ -1524,6 +1531,7 @@ export type PackageName =
   | '@toeverything/infra'
   | '@affine/nbstore'
   | '@affine/reader'
+  | '@affine/realtime'
   | '@affine/s3-compat'
   | '@affine/admin'
   | '@affine/android'