Add compact_blank polyfill for Rails 5.2-6.0 compatibility

The previous commit added `require "active_support/core_ext/enumerable"` but
this doesn't provide `compact_blank` on Rails < 6.1 because that method was
only introduced in Rails 6.1.

This commit adds a proper polyfill that:
1. Checks if compact_blank already exists (Rails 6.1+)
2. If not, defines it on both Enumerable and Array using reject(&:blank?)
3. Also requires "active_support/core_ext/object/blank" for the blank? method

The polyfill correctly mirrors Rails 6.1+ behavior:
- Removes nil, empty strings (""), whitespace strings ("  ")
- Removes false (since false.blank? == true in ActiveSupport)
- Keeps truthy values like non-empty strings, true, numbers

This ensures the gem works correctly on all supported Rails versions (>= 5.2).

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

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

Author: justin808

lib/react_on_rails/configuration.rb

@@ -1,6 +1,22 @@
 # frozen_string_literal: true
 
 require "active_support/core_ext/enumerable"
+require "active_support/core_ext/object/blank"
+
+# Polyfill for compact_blank (added in Rails 6.1) to support Rails 5.2-6.0
+unless [].respond_to?(:compact_blank)
+  module Enumerable
+    def compact_blank
+      reject(&:blank?)
+    end
+  end
+
+  class Array
+    def compact_blank
+      reject(&:blank?)
+    end
+  end
+end
 
 # rubocop:disable Metrics/ClassLength