feat: enable bitwarden for walker

modules/capabilities/walker.nix

@@ -27,6 +27,13 @@ in
       programs.walker = {
         enable = true;
         runAsService = true;
+
+        config.providers.prefixes = [
+          {
+            provider = "bitwarden";
+            prefix = "?";
+          }
+        ];
       };
     };