[AlexGeslani]

Summary

• add a bounded, theme-aware next-piece preview frame
• scope iOS double-tap zoom prevention to enabled gameplay controls
• track touch timing per control while preserving navigation and ordinary zoom behavior

Verification

• 98/98 Node tests passed in the isolated dev candidate
• independent exact-hash review passed
• real-Chrome runtime acceptance passed with zero console errors
• physical iPad Safari acceptance passed on stacklogic-dev.game.lan

Promotion boundary

• dev only until this PR is reviewed and checks pass
• production has not been modified