Rewrite maifetch in Rust

[andrewlu-lang]

Summary

Rewrites maifetch from Go to Rust while keeping the existing CLI behavior and output shape aligned with the original implementation.

Changes

• Add a Rust CLI entrypoint with clap
• Preserve access token/config loading from JSON, environment variables, and CLI arguments
• Keep recent play/profile fetching from the MaiTea API
• Recreate colored score/rank/difficulty output
• Recreate profile icon ASCII rendering
• Update build instructions to use Cargo
• Remove the old Go implementation and Go module files

Verification

• cargo check
• cargo fmt -- --check
• cargo run -- --help
• cargo build --release

Closes #1

[nyairobi]

Nice job, Andrew.