- Update mutt to use muchsync tool via self.packages with -vv flags
- Fix muchsync wrapper to handle flags properly when auto-detecting hosts
- Now supports: muchsync -vv (auto-detects host) or muchsync -vv hostname

- Remove 2configs/mpv.nix and replace imports with tools.mpv package
- Update desktop configurations to use self.packages.${pkgs.system}.mpv
- Simplify home-media.nix by removing unused mpv import

Create mpv tool based on 2configs/mpv.nix configuration with:
- Custom mpv configuration and input bindings
- mpv scripts (sponsorblock, quality-menu, vr-reversal, visualizer)
- Separate mpv-dl-subs package that loads on-demand when pressing 'S'
- YouTube resolution limit and sponsorblock configuration

Replace deprecated writeBashBin with writeShellScriptBin to fix build error.