tests/radicle: stub radicle-node

Failing build is blocking CI, test only verifies generated config.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

tests/modules/programs/radicle/basic-configuration.nix

@@ -1,9 +1,19 @@
-{ config, pkgs, ... }:
-
 {
   config = {
     programs.radicle.enable = true;
 
+    test.stubs.radicle-node = {
+      buildScript = ''
+        mkdir -p "$out/bin"
+        cat > "$out/bin/rad" << 'EOF'
+        #!/bin/sh
+        # Stub rad command that does nothing
+        exit 0
+        EOF
+        chmod +x "$out/bin/rad"
+      '';
+    };
+
     nmt.script = ''
       assertFileContent \
         home-files/.radicle/config.json \