Add Hyprland with hy3 plugin for XMonad-like tiling

Configure Hyprland to use the hy3 plugin for dynamic tiling similar to
XMonad. Uses official Hyprland and hy3 flakes pinned to v0.53.0 for
proper plugin compatibility (nixpkgs packaging had header issues).

Key changes:
- Add hyprland and hy3 flake inputs with version pinning
- Rewrite hyprland.conf with hy3 layout and XMonad-like keybindings
- Add helper scripts for window management (bring, replace, gather, etc.)
- WASD directional navigation using hy3:movefocus/movewindow
- Tab groups, horizontal/vertical splits via hy3:makegroup
- Scratchpads via Hyprland special workspaces

Also removes org-agenda-api flake integration (moved elsewhere).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

nixos/extra.nix

@@ -1,7 +1,5 @@
 { config, pkgs, makeEnable, ... }:
 makeEnable config "myModules.extra" false {
-  programs.hyprland.enable = true;
-
   environment.systemPackages = with pkgs; [
     android-studio
     gradle