feat(copilot): add raw-loader and dynamic system prompt loading

[ysfscream]

I'll help you complete the GitHub PR description based on the template and the content you've provided:

PR Checklist

If you have any questions, you can refer to the Contributing Guide

What is the current behavior?

Currently, the system prompts are scattered in the i18n files, making them difficult to manage and modify efficiently. The preset section lacks structure and issues with system prompt loading and command customization. The empty page lacks helpful guidance for users.

Issue Number

What is the new behavior?

1. Reorganized all system prompts into a single English txt file for easier management and modification, rather than maintaining them in i18n
2. Refactored the preset section to improve maintainability and make it easier to add new presets
3. Implemented dynamic loading of system prompts
4. Optimized commands that require custom user input
5. Enhanced the empty page display with usage tips and suggestions

Does this PR introduce a breaking change?

• Yes
• No

Specific Instructions

This PR focuses on improving the organization and management of system prompts and presets. Please review the new file structure for system prompts and the refactored preset implementation.

Other information

This refactoring will make it easier to maintain and extend the system prompts and presets in the future, while also providing a better user experience with improved guidance.