feat: Add host sydpc

My, this is a lot TwT.  Much work was batched as part of the transition from
guix-rebound to nixos-testbed/sydpc.

- Discord/Vesktop module & config.
- Syncthing setup.
- Assorted Emacs changes.
- Waybar config.
- Niri config.
- Steam config.
- Some MPD.
- Stylix config.
- Files/Impermanence things.
- Enable Ghostty.
- God knows what else.

users/crumb/default.nix

@@ -14,7 +14,6 @@
 
   homeConfiguration = { config, lib, pkgs, ... }: {
     imports = [
-      # ./programs.nix
       ./files.nix
     ];
 
@@ -22,8 +21,8 @@
     xdg.enable = true;
     # Not yet in my version of HM.
     # xdg.preferXdgDirectories = true;
-    qt.style.name = "breeze-dark";
-    qt.style.package = pkgs.libsForQt5.breeze-qt5;
+    # qt.style.name = "breeze-dark";
+    # qt.style.package = pkgs.libsForQt5.breeze-qt5;
 
     sydnix = {
       gpg.enable = true;
@@ -42,7 +41,12 @@
         mpd.enable = true;
         nvim.enable = true;
         emacs.enable = true;
+        niri.enable = true;
+        waybar.enable = true;
+        discord.enable = true;
+        ghostty.enable = true;
       };
+      steam.enable = true;
     };
 
     # Don't touch!