Add touch feedback effect on background - #16

Description

Adds visual feedback when users touch the screen on mobile devices, creating an expanding ripple effect at the touch point.

Changes

• Created new touch_feedback module in effects
• Implemented TouchFeedback component for animation state
• Added spawn_touch_feedback system to create effects on touch
• Added update_touch_feedback system to animate and render effects
• Expanding circle ripple effect (2.0 to 10.0 radius)
• Fades out over 0.5 seconds with quadratic easing
• Converts screen position to world position for accurate placement
• Automatic entity cleanup after animation completes
• Integrated into effects plugin system

Visual Effect Details

• Trigger: TouchPhase::Started (when finger touches screen)
• Color: Cyan/blue (RGB: 0.3, 0.9, 1.0)
• Animation: Expanding circle from 2.0 to 10.0 radius
• Duration: 0.5 seconds
• Fade: Quadratic fade-out (alpha: 0.7 to 0.0)
• Position: World space at touch location

Behavior

• Spawns: On every touch start event
• Animates: Expands and fades simultaneously
• Despawns: Automatically after 0.5 seconds
• Performance: Minimal impact, entities cleaned up automatically
• Mobile-specific: Only triggers on touch input

Benefits

• Provides immediate visual feedback for touch input
• Helps users confirm their touches are registered
• Enhances mobile user experience
• Makes touch interactions feel more responsive
• Adds polish and game feel to mobile version
• Helps with touch accuracy awareness

Technical Implementation

• Uses Bevy's touch input event system
• Converts viewport coordinates to world coordinates
• Uses gizmos for efficient rendering
• Component-based animation with time tracking
• Automatic entity lifecycle management
• Integrated into GameplaySystem set

Performance

• Lightweight: Only spawns on touch events
• Efficient: Uses gizmos (no sprites/meshes)
• Clean: Automatic despawn prevents entity buildup
• Minimal: Simple circle rendering
• Scalable: Works with multiple simultaneous touches

Testing

• Touch screen on mobile device
• Verify cyan ripple appears at touch point
• Check that ripple expands and fades smoothly
• Confirm automatic cleanup (no entity buildup)
• Test with multiple simultaneous touches
• Verify no performance impact

Related Issue

Fixes: Android/Mobile Feedback - Touch creates some feedback, an effect on touching the background (mobile)