Polish ringtail NixOS config and add documentation (#208)
## Summary
- Fix Super+Return keybinding to launch wezterm in sway
- Set fish as default login shell
- Remove `initialPassword` (real password already set)
- Add 1Password CLI + GUI, chezmoi, and dev tool packages (neovim, eza, fd, fzf, zoxide, starship, atuin, bat, ripgrep)
- Add ringtail reference card, update host inventory and reference index
- Changelog fragment
## Post-merge deployment
- `mise run provision-ringtail` to rebuild NixOS
- On ringtail: launch 1Password GUI, enable CLI integration (Settings > Developer > CLI integration)
- Chezmoi needs `.chezmoiignore` updates in the dotfiles repo (separate task)
Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/208