feat: tip confirmation animation with haptic feedback

Success overlay with animated checkmark and 'Dein Tipp ist drin! 🎯'
message. Haptic vibration on mobile. Auto-closes after 1.2s.

- Add showSuccess state to TipModal
- Trigger vibration feedback on successful submit
- Display success overlay with popIn animation for checkmark
- Auto-close modal after success animation completes
- Add CSS animations (fadeIn, popIn) to TipModal.module.css

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.superpowers/brainstorm/4751-1775923699/state/server-stopped

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+{"reason":"idle timeout","timestamp":1775926519574}