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.

install/modules/go.sh

@@ -0,0 +1,34 @@
+install_go() {
+  local latest
+  latest=$(curl -fsSL 'https://go.dev/VERSION?m=text' | head -n1)
+
+  if has_cmd go && go version | grep -q "$latest"; then
+    ok "go already at $latest"
+    return
+  fi
+
+  local arch
+  case "$(uname -m)" in
+    x86_64) arch=amd64 ;;
+    aarch64) arch=arm64 ;;
+    *) err "unsupported arch $(uname -m)"; return 1 ;;
+  esac
+
+  local tarball="/tmp/${latest}.linux-${arch}.tar.gz"
+  curl -fsSL "https://go.dev/dl/${latest}.linux-${arch}.tar.gz" -o "$tarball"
+
+  local backup=""
+  if [[ -d /usr/local/go ]]; then
+    backup="/usr/local/go.bak.$$"
+    sudo mv /usr/local/go "$backup"
+    rollback_push "sudo rm -rf /usr/local/go; sudo mv '$backup' /usr/local/go"
+  else
+    rollback_push "sudo rm -rf /usr/local/go"
+  fi
+
+  sudo tar -C /usr/local -xzf "$tarball"
+  rm -f "$tarball"
+  if [[ -n "$backup" ]]; then sudo rm -rf "$backup"; fi
+
+  profile_add 'export PATH="/usr/local/go/bin:$HOME/go/bin:$PATH"'
+}