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

config/database.yml

@@ -28,6 +28,7 @@ development:
 test:
   <<: *default
   database: aperonight_test
+  isolation_level: READ UNCOMMITTED
   # adapter: sqlite3
   # pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
   # database: data/test.sqlite3