Create advanced examples and API reference

[thomasnemer]

Summary

This PR implements issue #16 by adding comprehensive intermediate and advanced examples plus API reference documentation for the Prong UI framework.

Changes

Intermediate Examples (examples/intermediate/)

✅ 01_nested_panels - Complex nested layout composition

• Demonstrates FlexLayout containing GridLayout containing StackLayout
• Multiple levels of panel nesting with different layout strategies
• Shows layout composition patterns

✅ 02_responsive_ui - Window resize behavior

• Demonstrates ResizeBehavior (FIXED, SCALE, FILL)
• Shows AxisResizeBehavior for per-axis control
• Includes ResponsiveConstraints with min/max bounds
• Real-time window resize handling

✅ 03_event_handling - Advanced event patterns

• Custom InteractivePanel with handleEventSelf override
• Mouse interactions: click, drag, hover states
• Keyboard shortcuts and focus management
• Event propagation demonstration

✅ 04_dynamic_layout - Runtime UI changes

• Add/remove components dynamically
• Switch between 5 different layout managers at runtime
• Control panel with 9 interactive buttons
• Shows invalidateLayout() usage

Advanced Examples (examples/advanced/)

✅ 01_custom_component - ColorPicker custom component

• Full CRTP implementation inheriting from Component
• Custom render() and handleEventSelf() implementations
• Builder pattern for construction
• Callback system for value changes

✅ 02_custom_layout - CircularLayout implementation

• Custom layout manager using CRTP pattern
• Implements measureLayout() and layout() methods
• Positions 8 buttons in a circle using trigonometry

✅ 03_custom_renderer - IRenderer interface demonstration

• Shows frame lifecycle (beginFrame/endFrame)
• Demonstrates all IRenderer methods
• Comprehensive README explaining renderer integration

✅ 04_performance - Performance optimization demo

• 100 components in GridLayout
• FPS counter showing performance
• README with optimization guidelines

API Reference Documentation (docs/api/)

✅ README.md - Navigation hub for all API documentation

• Quick links to all sections
• Architecture overview
• Common patterns and examples
• Building applications guide

✅ QUICK_REFERENCE.md - Condensed one-page reference

• All core classes with signatures
• All 7 UI components
• All 5 layout managers
• Event handling patterns
• Common code patterns
• Performance tips

✅ core/Component.md - Detailed Component API documentation

• Full class declaration
• Coordinate systems explanation
• Ownership model
• Event handling
• Resize behavior
• Usage patterns and best practices

Build Status

✅ All 8 new examples compile successfully
✅ All examples run without errors
✅ Code formatted with clang-format
✅ Git hooks passed

Files Changed

• 28 files added
• 4016 lines of code and documentation
• 0 deletions (purely additive)

Testing

All examples have been built and verified to compile successfully with:

mise build-examples

Resolves #16