Phase 04 — Midnight Arcade: UI redesign, dice animation, and sound

A full visual and animation overhaul, plus the app's first sound effects.

Added

• Full "Midnight Arcade" dark UI redesign (no more light mode) — near-black radial-gradient background, cyan→violet gradient accents, Space Grotesk/Space Mono fonts, a large circular Roll button, edge-docked pills for the last roll and next player
• One shared dialog shell and bottom nav used across every dialog (Players, Hand, Roll history, Game edit, Game hash), instead of each rolling its own
• Dice now tumble while rolling — CSS movement and rotation with genuine deceleration as each die settles, then a short pause before the result reveals
• The result reveal is a full-width banner with real die sprites and an avg/median/min/max stat row, blurring the drop area behind it
• Sound effects throughout — button taps, a roll press sound, per-die tumble/landing sounds (randomized, pitched by die size), and a fanfare on the result — real audio clips with synthesized fallbacks if a file's missing
• A Sound on/off switch in the settings menu, remembered across sessions

Fixed

• Bottom bar disappearing/unusable while a roll result was showing
• The last-roll pill overlapping the Roll button with long player names
• A dialog's whole screen sliding (including a duplicate bottom bar) instead of just its own content

Full details in CHANGELOG.md.