### TL;DR
Relocated AI item components from BlockSuite to the frontend codebase and updated related imports.
### What changed?
- Moved AI item components from `blocksuite/affine/components/src/ai-item` to `packages/frontend/core/src/blocksuite/presets/ai/_common/components/ai-item`
- Updated all imports referencing the old AI item component location to point to the new location
- Removed AI item exports from BlockSuite's package.json and effects registration
- Added AI item effects registration to frontend presets
### How to test?
1. Verify AI functionality works as expected in:
- Chat panels
- AI toolbars
- Edgeless copilot
- Slash menu
2. Confirm no AI-related console errors appear
3. Test error handling scenarios (unauthorized, payment required, network errors)
### Why make this change?
This change consolidates AI-related components into the frontend codebase where they are primarily used, rather than keeping them in BlockSuite. This improves code organization by placing components closer to their implementation and usage, while reducing unnecessary coupling between packages.
