Add mise for runtime version management

[ComeBertrand]

Problem

Currently using system-wide Python 3.12, Rust, and Node.js versions. While uv handles Python package management well, we can't:

• Run different Python versions per project (e.g., legacy 3.10 project + modern 3.12 project)
• Test against multiple Node.js versions
• Quickly switch Rust toolchains
• Match production environments exactly

Impact

• "Works on my machine" problems
• Can't maintain legacy projects alongside modern ones
• No per-project .tool-versions file for team consistency
• Manual NixOS rebuilds just to change language versions

Action Plan

Priority: MEDIUM - Quality of life improvement

1. Add mise (formerly rtx) to configuration.nix

users.users.cbertrand.packages = with pkgs; [
  mise  # Fast Rust-based, replaces asdf
];

2. Enable mise in bashrc

# In sources/bashrc.sh
eval "$(mise activate bash)"

3. Configure mise for auto-installation

# ~/.config/mise/config.toml
[tools]
python = "3.12"
node = "22"
rust = "1.75"

[settings]
experimental = true

4. Per-project versions using .mise.toml

[tools]
python = "3.10.12"  # Legacy project
node = "20.11.0"

5. Keep NixOS packages as fallback

mise can reference system versions

Why mise over asdf

• 24x faster (Rust vs bash)
• Built-in Python/Node support (no plugins needed)
• Replaces direnv for environment variables
• ~5ms overhead vs ~120ms for asdf

Sources

• Better Stack - mise vs asdf
• Medium - Why I switched to mise
• mise documentation