Add minimum_versions? predicate method for Ruby idiom

Add a predicate method with ? suffix for boolean checks, following
Ruby convention. Update run_rspec.rake to use the predicate method
with &:minimum_versions? instead of &:minimum_versions.

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

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

Author: justin808

react_on_rails/rakelib/example_type.rb

@@ -19,6 +19,11 @@ def self.all
 
       attr_reader :packer_type, :name, :generator_options, :minimum_versions
 
+      # Ruby convention: predicate method with ? suffix for boolean checks
+      def minimum_versions?
+        minimum_versions
+      end
+
       def initialize(packer_type: nil, name: nil, generator_options: nil, minimum_versions: false)
         @packer_type = packer_type
         @name = name

react_on_rails/rakelib/run_rspec.rake

@@ -92,11 +92,11 @@ namespace :run_rspec do
 
   # Helper methods for filtering examples
   def latest_examples
-    ExampleType.all[:shakapacker_examples].reject(&:minimum_versions)
+    ExampleType.all[:shakapacker_examples].reject(&:minimum_versions?)
   end
 
   def minimum_examples
-    ExampleType.all[:shakapacker_examples].select(&:minimum_versions)
+    ExampleType.all[:shakapacker_examples].select(&:minimum_versions?)
   end
 
   desc "Runs Rspec for latest version example apps only (excludes minimum version tests)"