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/deno.sh

@@ -0,0 +1,7 @@
+install_deno() {
+  if has_cmd deno; then ok "deno already installed"; return; fi
+  track_new_dir "$HOME/.deno"
+  curl -fsSL https://deno.land/install.sh | sh
+  profile_add 'export DENO_INSTALL="$HOME/.deno"'
+  profile_add 'export PATH="$DENO_INSTALL/bin:$PATH"'
+}