Tail is now drawn as a separate DrawLine from interpolated tail position
to the grid-snapped second-to-last segment. Body path (segment[N-2]→head)
stays grid-snapped, preserving sharp corners while tail glides smoothly.
Tail interpolation caused diagonal shortcuts at corners because
the interpolated tail position would drift while the adjacent
segment was already at its new grid position. By keeping only
the head interpolated, L-shaped bends render correctly.
- Two-timer architecture: game timer + 60fps render timer for smooth interpolation
- Snake body: StreamGeometry path with teal gradient, rounded joins
- Directional head with white eyes and dark pupils
- Food: pulsating glow, highlight, green leaf animation
- Modern dark theme (#0D1117), glassmorphism HUD
- Speed indicator bar, score +N popup
- High score persistence to JSON
- All keyboard shortcuts: Arrows, WASD, Space/P pause, Enter start, R restart, Esc quit
- Window resizable, 640x540 default
New files: AnimationHelper.cs, HighScoreManager.cs, SnakeRenderer.cs
