Close [AI-260](https://linear.app/affine-design/issue/AI-260)
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added theme support to AI chat and message components, enabling
dynamic theming based on the current app theme.
* Introduced a reactive theme signal to the theme service for improved
theme handling.
* Integrated notification and theme services across various AI chat,
playground, and message components for consistent user experience.
* **Refactor**
* Simplified component APIs by removing dependencies on editor host and
related properties across AI chat, message, and tool components.
* Centralized and streamlined clipboard and markdown conversion
utilities, reducing external dependencies.
* Standardized the interface for context file addition and improved type
usage for better consistency.
* Reworked notification service to a class-based implementation for
improved encapsulation.
* Updated AI chat components to use injected notification and theme
services instead of host-based retrieval.
* **Bug Fixes**
* Improved reliability of copy and notification actions by decoupling
them from editor host dependencies.
* **Chores**
* Updated and cleaned up internal imports and removed unused properties
to enhance maintainability.
* Added test IDs for sidebar close button to improve test reliability.
* Updated test prompts in end-to-end tests for consistency.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **Refactor**
- Unified internal data access by replacing all references from `doc` to `store` across all components, blocks, widgets, and utilities. This affects how readonly state, block operations, and service retrieval are handled throughout the application.
- **Tests**
- Updated all test utilities and test cases to use `store` instead of `doc` for document-related operations.
- **Chores**
- Updated context providers and property names to reflect the change from `doc` to `store` for improved consistency and maintainability.
No user-facing features or behaviors have changed.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Wu Yue