Add modular dev environment installer, dotfiles, and desnap script

Adds a TUI-driven, rollback-capable installer (install/install.sh +
install/modules/*.sh) covering JS/Python/systems toolchains, dev tooling,
browsers, chat apps, GNOME extras, and misc setup (wakatime key, ssh/gpg
perms, apt mirror benchmarking), all sourced from each vendor's official
install method. bootstrap.sh stows the zsh/git/tmux/vscode dotfiles and
runs the installer; desnap.sh purges snapd and replaces default snaps with
apt/Flatpak equivalents.

bootstrap.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+export DOTFILES_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=install/lib.sh
+source "$DOTFILES_DIR/install/lib.sh"
+
+DRY_RUN=0
+for a in "$@"; do
+  if [[ "$a" == "--dry-run" ]]; then DRY_RUN=1; fi
+done
+export DRY_RUN
+
+STOW_PACKAGES=(zsh git tmux vscode)
+
+if [[ "$DRY_RUN" == "1" ]]; then
+  log "[dry-run] would install base packages: stow zsh curl git"
+  log "[dry-run] would stow: ${STOW_PACKAGES[*]} -> \$HOME"
+else
+  log "installing base packages"
+  apt_install stow zsh curl git
+
+  log "stowing dotfiles from $DOTFILES_DIR"
+  stow -v -t "$HOME" -d "$DOTFILES_DIR" "${STOW_PACKAGES[@]}"
+fi
+
+if [[ "$DRY_RUN" == "1" ]]; then
+  log "[dry-run] would prompt for git identity + signing key -> ~/.gitconfig.local"
+elif [[ ! -f "$HOME/.gitconfig.local" ]]; then
+  read -rp "git user.name: " git_name
+  read -rp "git user.email [[email protected]]: " git_email
+  git_email="${git_email:-andwatiian@gmail.com}"
+  read -rp "git signing key (GPG key id) [1F20FED0AA05B0DA]: " git_signkey
+  git_signkey="${git_signkey:-1F20FED0AA05B0DA}"
+  {
+    echo "[user]"
+    echo "    name = $git_name"
+    echo "    email = $git_email"
+    if [[ -n "$git_signkey" ]]; then echo "    signingkey = $git_signkey"; fi
+  } > "$HOME/.gitconfig.local"
+  ok "wrote $HOME/.gitconfig.local"
+fi
+
+if [[ "$DRY_RUN" == "1" ]]; then
+  if [[ "$SHELL" != *zsh* ]]; then log "[dry-run] would set default shell to zsh"; fi
+elif [[ "$SHELL" != *zsh* ]]; then
+  log "setting zsh as default shell"
+  chsh -s "$(command -v zsh)" "$USER"
+fi
+
+log "running tool installer"
+"$DOTFILES_DIR/install/install.sh" "$@"
+
+ok "all done — open a new shell (or 'exec zsh') to pick up PATH changes"