feat(zz-blankpad): ghostty terminal bind and bun PATH for omp

blankpad runs quickshell 0.3.1 from repos with the noctalia shell; flip
Mod+Return to spawn ghostty (installed) instead of alacritty, and put the
bun global bin dir on PATH so the pi-coding-agent/omp shim resolves in
interactive zsh.

dotfiles/zz-blankpad/niri/.config/niri/cfg/keybinds.kdl

@@ -9,7 +9,7 @@ binds {
     Mod+Shift+ESCAPE                     { show-hotkey-overlay; }
 
     // ─── Applications ───
-    Mod+Return                          hotkey-overlay-title="Open Terminal: Alacritty" { spawn "alacritty"; }
+    Mod+Return                          hotkey-overlay-title="Open Terminal: Ghostty" { spawn "ghostty"; }
     Mod+B                               hotkey-overlay-title="Open Browser: firefox" { spawn "firefox"; }
 
     // --- Noctalia ---

dotfiles/zz-blankpad/zsh/.zshrc

@@ -1 +1,3 @@
 source /usr/share/cachyos-zsh-config/cachyos-config.zsh
+
+[ -d "$HOME/.bun/bin" ] && export PATH="$HOME/.bun/bin:$PATH"