feat(dotfiles): import env layer as stow-style packages with deploy.sh

Import Dankware's environment layer into the repo as home-relative package
trees (niri, gtk-3/4, ghostty, alacritty, fish, zsh, bash, profile,
systemd-user, dconf). scripts/deploy.sh implements stow-equivalent semantics
(check|adopt|sync modes): identical files adopt to symlinks, new files link,
divergent files quarantine-and-replace under .quarantine/<host>/<ts>/ (gitignored).
zz-<hostname> override packages deploy last with override semantics.

Secrets never enter git: GITEA_TOKEN moved from .zshrc into untracked
~/.config/environment.d/secrets.env (0600); tracked .zshrc sources it
guarded. core.hooksPath armed by deploy.sh so the pre-commit secret gate is
live on every machine that deploys.

.gitignore

@@ -53,3 +53,6 @@ puppeteer/
 .AGENTTRASH/
 *.save
 *.bak-*
+
+# deploy quarantine — never tracked
+.quarantine/