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.

dotfiles/niri/.config/niri/cfg/display.kdl

@@ -0,0 +1,21 @@
+// ────────────── Output Configuration ──────────────
+output "Samsung Electric Company Odyssey G75F HNTY601056" {
+    mode "3840x2160@60"
+    scale 1
+    transform "normal"
+    position x=0 y=0
+}
+
+output "DP-1" {
+    transform "90"
+    position x=0 y=0
+}
+
+output "DP-3" {
+    transform "270"
+    position x=1200 y=0
+}
+
+output "eDP-1" {
+    // no position — auto-placed to the right of DP-* outputs
+}