Initial chezmoi-managed dotfiles with bootstrap scripts

- Rename master to legacy-2025 on remote (frozen pre-chezmoi snapshot)
- New orphan 'main' branch with bootstrap-enabled config
- .chezmoi.yaml.tmpl detects os_family (debian | arch) from /etc/os-release
- dot_zshrc.tmpl refactored from current miche config with os_family
  conditional for pacman vs apt aliases
- dot_config/: bat, btop, ghostty (with gruvbox themes), kitty (with gruvbox
  colors), nvim (LazyVim), paru
- dot_gitconfig.tmpl, dot_tmux.conf (verbatim from current state)
- run_once_00-install-bootstrap-tools.sh.tmpl: age, git, curl, ca-certificates
- run_once_10-add-chaotic-aur.sh.tmpl (arch-only): add Chaotic-AUR + install paru
- run_once_20-install-user-packages.sh.tmpl: zsh, tmux, neovim (with version
  check + binary tarball fallback for debian), oh-my-zsh + plugins, tpm,
  rustup, all CLI tools
- run_onchange_30-ensure-cargo.sh.tmpl: rustup fallback
- README.md with onboarding runbook

dot_config/ghostty/themes/gruvbox-material-medium-dark

@@ -0,0 +1,21 @@
+palette = 0=#1b1b1b
+palette = 1=#ea6962
+palette = 2=#a9b665
+palette = 3=#d8a657
+palette = 4=#7daea3
+palette = 5=#d3869b
+palette = 6=#89b482
+palette = 7=#d4be98
+palette = 8=#32302f
+palette = 9=#ea6962
+palette = 10=#a9b665
+palette = 11=#d8a657
+palette = 12=#7daea3
+palette = 13=#d3869b
+palette = 14=#89b482
+palette = 15=#d4be98
+background = #282828
+foreground = #d4be98
+cursor-color = #d4be98
+selection-background = #3c3836
+selection-foreground = #d4be98