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.

git/.gitconfig

@@ -0,0 +1,24 @@
+[core]
+    editor = vim
+    excludesfile = ~/.gitignore_global
+
+[init]
+    defaultBranch = main
+
+[pull]
+    rebase = false
+
+[alias]
+    st = status
+    co = checkout
+    br = branch
+    lg = log --oneline --graph --decorate --all
+
+[commit]
+    gpgsign = true
+
+[tag]
+    gpgSign = true
+
+[include]
+    path = ~/.gitconfig.local