Add comprehensive Events controller tests

- Tests index and show actions thoroughly
- Tests pagination functionality
- Tests authentication requirements (none required)
- Tests template rendering
- Tests edge cases like invalid parameters
- Tests association preloading
- Added rails-controller-testing gem for assigns() and assert_template
- 17 tests covering all Events controller functionality

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

Co-Authored-By: Claude <noreply@anthropic.com>

Gemfile

@@ -71,6 +71,8 @@ group :test do
   # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
   gem "capybara"
   gem "selenium-webdriver"
+  # For controller testing helpers
+  gem "rails-controller-testing"
 end
 
 gem "devise", "~> 4.9"