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/bat/config

@@ -0,0 +1,28 @@
+# This is `bat`s configuration file. Each line either contains a comment or
+# a command-line option that you want to pass to `bat` by default. You can
+# run `bat --help` to get a list of all possible configuration options.
+
+# Set pretty print for more "cat" like looks
+-pp
+
+# Specify desired highlighting theme (e.g. "TwoDark"). Run `bat --list-themes`
+# for a list of all available themes
+--theme="gruvbox-dark"
+
+# Enable this to use italic text on the terminal. This is not supported on all
+# terminal emulators (like tmux, by default):
+#--italic-text=always
+
+# Uncomment the following line to disable automatic paging:
+#--paging=never
+
+# Uncomment the following line if you are using less version >= 551 and want to
+# enable mouse scrolling support in `bat` when running inside tmux. This might
+# disable text selection, unless you press shift.
+#--pager="less --RAW-CONTROL-CHARS --quit-if-one-screen --mouse"
+
+# Syntax mappings: map a certain filename pattern to a language.
+#   Example 1: use the C++ syntax for .ino files
+#   Example 2: Use ".gitignore"-style highlighting for ".ignore" files
+#--map-syntax "*.ino:C++"
+#--map-syntax ".ignore:Git Ignore"