Dropdown Stabilization & JavaScript Cleanup

What Was Built

Simplified the dropdown Stimulus controller from 109 lines of fragile async stimulus-use loading to 30 lines of pure CSS class toggling. Removed all window namespace pollution (window.SourceMonitorControllers, window.SourceMonitorStimulus). Added unique data-testid attributes to dropdown containers for test isolation. Click-outside dismissal now uses a document-level listener managed in connect()/disconnect() for proper cleanup during Turbo Drive navigation.

Commits

• 491fae1 refactor(05-03): simplify dropdown controller and remove JS globals

Tasks Completed

1. Simplified dropdown_controller.js to CSS class toggle only (109 -> 30 lines)
2. Removed window.SourceMonitorControllers from notification_controller.js
3. Removed window.SourceMonitorStimulus from application.js
4. Updated dropdown HTML with unique data-testid and removed declarative click@window
5. Verified: yarn build clean, 1491 tests pass, no remaining global/stimulus-use references

Files Modified

• app/assets/javascripts/source_monitor/controllers/dropdown_controller.js -- rewritten to pure CSS toggle
• app/assets/javascripts/source_monitor/controllers/notification_controller.js -- removed global registration
• app/assets/javascripts/source_monitor/application.js -- removed window.SourceMonitorStimulus
• app/views/source_monitor/sources/_row.html.erb -- added data-testid, removed click@window
• app/views/source_monitor/sources/_health_status_badge.html.erb -- added unique data-testid per source, removed click@window
• app/assets/builds/source_monitor/application.js -- rebuilt
• app/assets/builds/source_monitor/application.js.map -- rebuilt

Deviations

None.