refactor(editor): reorg blocksuite ai code (#10372)

### TL;DR

Relocated AI-related code from `presets` directory to a dedicated `ai` directory for better organization and maintainability.

### What changed?

- Moved AI-related code from `blocksuite/presets/ai` to `blocksuite/ai`
- Relocated AI chat block code from `blocksuite/blocks` to `blocksuite/ai/blocks`
- Updated imports across files to reflect new directory structure
- Renamed `registerBlocksuitePresetsCustomComponents` to `registerAIEffects`
- Fixed path references in GitHub workflow file

### How to test?

1. Build and run the application
2. Verify AI functionality works as expected:
   - Test AI chat blocks
   - Check AI panel functionality
   - Verify AI copilot features
   - Ensure AI-related UI components render correctly

### Why make this change?

This restructuring improves code organization by:
- Giving AI features a dedicated directory that better reflects their importance
- Making the codebase more maintainable by grouping related AI functionality
- Reducing confusion by removing AI code from the more general `presets` directory
- Creating clearer boundaries between AI and non-AI related code

packages/frontend/core/src/modules/cloud/services/auth.ts

@@ -1,4 +1,4 @@
-import { AIProvider } from '@affine/core/blocksuite/presets';
+import { AIProvider } from '@affine/core/blocksuite/ai';
 import type { OAuthProviderType } from '@affine/graphql';
 import { track } from '@affine/track';
 import { OnEvent, Service } from '@toeverything/infra';