Improve bin/dev generated script with hello_world default route

- Add DEFAULT_ROUTE variable in generated bin/dev template
- Automatically append --route hello_world when no route specified
- Remove confusing fallback code from generator template
- Keep fallback in spec/dummy/bin/dev with clear comments for gem development
- Improve developer experience: ./bin/dev now goes directly to generated component

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

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

lib/generators/react_on_rails/templates/base/base/bin/dev

@@ -18,14 +18,19 @@
 # 3. Extend ReactOnRails::Dev classes in your Rails app for advanced customization
 # 4. Use classes directly: ReactOnRails::Dev::ServerManager.start(:development, "Custom.procfile")
 
-begin
-  require "bundler/setup"
-  require "react_on_rails/dev"
-rescue LoadError
-  # Fallback for when gem is not yet installed
-  puts "Loading ReactOnRails development tools..."
-  require_relative "../../lib/react_on_rails/dev"
-end
+require "bundler/setup"
+require "react_on_rails/dev"
+
+# Default route configuration
+# This is set by the ReactOnRails installer to point to your generated component.
+# Change this to your preferred default route, or pass --route=<route> to override.
+DEFAULT_ROUTE = "hello_world"
 
 # Main execution
-ReactOnRails::Dev::ServerManager.run_from_command_line(ARGV)
+# Add the default route to ARGV if no --route option is provided
+argv_with_defaults = ARGV.dup
+unless argv_with_defaults.any? { |arg| arg.start_with?("--route") }
+  argv_with_defaults.push("--route", DEFAULT_ROUTE)
+end
+
+ReactOnRails::Dev::ServerManager.run_from_command_line(argv_with_defaults)