[pixi] Change magic to pixi for environment and package management

[forfudan]

This pull request introduces a migration from the magic CLI to the pixi CLI across various files and workflows, updating commands, configuration, and documentation to reflect the new tool. The changes ensure compatibility with pixi and streamline its integration into the project.

Migration to pixi CLI

Workflow Updates:

• .github/workflows/run_tests.yaml: Replaced all instances of magic commands with their pixi equivalents, including installation, adding paths, running tests, and pre-commit hooks. [1] [2]

Configuration Updates:

• .pre-commit-config.yaml: Updated the mojo-format hook to use pixi run mojo format instead of magic run mojo format.
• mojoproject.toml → pixi.toml: Fully migrated the project configuration from mojoproject.toml to pixi.toml, reflecting changes in tasks, dependencies, and CLI commands. [1] [2]

Documentation Updates:

• README.md: Modified installation instructions and examples to use pixi commands instead of magic. Updated version compatibility table for clarity. [1] [2]
• docs/readme_zht.md: Translated documentation updates to reflect the switch to pixi in Chinese-language instructions. [1] [2]