🎯 Complete Settings Modal Integration

[gitcoder89431]

🎯 Complete Settings Modal Integration

Final integration task bringing together all settings modal components and completing the migration from the old T-key system.

✅ Integration Tasks Completed

Theme Migration:

• ❌ Removed ToggleTheme event from event system
• ❌ Removed T key binding handler from app logic
• ❌ Updated demo files to use S key consistently
• ❌ Clean up all legacy theme switching code paths

UI Consistency:

• ✅ Footer correctly shows: ESC/q: Quit | S: Settings
• ✅ Settings modal shows: ESC: Back to Main | ↑↓/kj: Navigate | Enter/Space: Select
• ✅ No references to old T key functionality
• ✅ S key for settings access throughout

End-to-End Flow Verification:

1. ✅ S key opens settings modal over main interface
2. ✅ Modal contains theme selection with radio button style
3. ✅ Theme changes reflect immediately during navigation
4. ✅ T key completely removed from main app
5. ✅ ESC closes modal and returns to previous state
6. ✅ Footer updated to show new keybindings
7. ✅ Clean visual rendering with no artifacts

🧪 Testing Results

• Unit Tests: All 5 tests passing ✅
• Build: Successful compilation ✅
• Clippy: No warnings ✅
• Demo Examples: Working correctly ✅

🎨 Complete Features

This PR completes the full settings modal system:

• State Machine Integration (Issue 🔄 Extend App State Machine for Settings #19): ✅ Complete
• Modal UI Component (Issue 🎭 Implement Settings Modal UI Component #20): ✅ Complete
• Input Handling (Issue ⌨️ Implement Settings Modal Input Handling #21): ✅ Complete
• Final Integration (Issue 🎯 Complete Settings Modal Integration #22): ✅ Complete

🚀 User Experience

• S key: Opens settings modal with immediate theme preview
• Navigation: Vim-style k/j + arrow keys for smooth navigation
• Selection: Enter/Space to apply theme changes
• Exit: ESC to close modal and return to main interface
• Performance: Event-driven rendering for optimal efficiency

Closes #22