Fix doctor rake task LoadError with excluded task_helpers (#1795)

Resolves critical LoadError in `rake react_on_rails:doctor` when using the packaged gem.

**Problem:**
- The doctor.rake task (added in 27dba50) required "../../rakelib/task_helpers"
- The rakelib directory has been excluded from gem packaging since 2c04db6 (1.5+ years ago)
- This caused `LoadError: cannot load such file -- rakelib/task_helpers` in packaged gems

**Solution:**
- Remove unnecessary require_relative "../../rakelib/task_helpers" from doctor.rake
- Remove unused include ReactOnRails::TaskHelpers line
- Add test coverage to prevent future regressions

**Impact:**
- ✅ Doctor task now works correctly in packaged gems
- ✅ No functionality lost - TaskHelpers was not actually used
- ✅ Added regression test to ensure rake file loads without missing dependencies
- ✅ All existing tests pass

This fix enables users to run `rake react_on_rails:doctor` successfully in production environments and when using the published gem, restoring critical diagnostic functionality.

Author: justin808

lib/tasks/doctor.rake

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require_relative "../../rakelib/task_helpers"
 require_relative "../react_on_rails"
 require_relative "../react_on_rails/doctor"
 
@@ -38,8 +37,6 @@ rescue LoadError
 end
 
 namespace :react_on_rails do
-  include ReactOnRails::TaskHelpers
-
   desc "Diagnose React on Rails setup and configuration"
   task :doctor do
     verbose = ENV["VERBOSE"] == "true"

spec/lib/react_on_rails/doctor_rake_task_spec.rb

@@ -16,6 +16,12 @@
       expect(Rake::Task.task_defined?("react_on_rails:doctor")).to be true
     end
 
+    it "can be loaded without requiring missing task_helpers" do
+      # This test ensures the rake file doesn't try to require excluded files
+      # that would cause LoadError in packaged gems
+      expect { load rake_file }.not_to raise_error
+    end
+
     it "can be invoked without errors" do
       # Mock the Doctor class to avoid actual diagnosis
       doctor_instance = instance_double(ReactOnRails::Doctor)