Add comprehensive unit test coverage for controllers, models, and services

- Translate French comments to English in controllers and tests
- Fix test failures: route helpers, validations, MySQL transaction issues
- Add Timecop for time-dependent tests and update database config for isolation

test/controllers/application_controller_onboarding_test.rb

@@ -41,7 +41,7 @@ class ApplicationControllerOnboardingTest < ActionDispatch::IntegrationTest
   test "should redirect signed in incomplete users from home to onboarding" do
     sign_in @user_without_onboarding
     get root_path
-    assert_redirected_to dashboard_path  # Home redirects to dashboard for signed in users
+    assert_redirected_to onboarding_path
   end
 
   test "should not interfere with devise controllers" do