fix: code review fixes

- Fix hardcoded user path in webapps.nix (use homeDirectory)
- Normalize wallpapers option to use .enable suffix
- Remove duplicate FZF keybind declaration
- Update comments to match actual implementation

home/desktop/apps/webapps.nix

@@ -1,7 +1,7 @@
 # Web application desktop entries — Teams, Outlook, Basecamp, and OpenCode launchers.
 {
+  config,
   pkgs,
-  lib,
   ...
 }: let
   icons = {
@@ -42,7 +42,7 @@ in {
       comment = "Open Basecamp as a Desktop App";
       categories = ["Application" "Network"];
       terminal = false;
-      icon = "/home/sascha.koenig/.local/share/icons/basecamp-logo.png";
+      icon = "${config.home.homeDirectory}/.local/share/icons/basecamp-logo.png";
     };
     opencode = {
       name = "Opencode";