Replace spec/dummy/bin/dev symlink with wrapper script

Change spec/dummy/bin/dev from a symlink to a wrapper script that calls
the template bin/dev with --route=/ argument. This ensures the dummy app
always uses the root route instead of the default hello_world route.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

spec/dummy/bin/dev

@@ -0,0 +1,5 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+# This script calls the base dev script with a fixed route for the dummy app
+exec File.join(__dir__, "../../../lib/generators/react_on_rails/templates/base/base/bin/dev"), "--route=/", *ARGV