feat: 5 categorías rotativas por partida + pool de 200 preguntas + mejoras UI

Cambios principales:
- Tablero ahora muestra 5 categorías aleatorias (de 8 disponibles)
- Pool de 200 preguntas (8 cats × 5 diffs × 5 opciones)
- Preguntas rotan aleatoriamente entre partidas
- Diseño mejorado estilo Jeopardy con efectos visuales
- Socket singleton para conexión persistente
- Nuevos sonidos: game_start, player_join, question_reveal, hover, countdown
- Control de volumen vertical
- Barra de progreso del timer en modal de preguntas
- Animaciones mejoradas con Framer Motion

Backend:
- question_service: selección aleatoria de 5 categorías
- room_manager: fix retorno de create_room
- game_events: carga board desde DB, await en enter_room

Frontend:
- Game.tsx: tablero dinámico, efectos hover, mejor scoreboard
- useSocket: singleton service, eventos con sonidos
- SoundControl: slider vertical
- soundStore: 5 nuevos efectos de sonido

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/stores/soundStore.ts

@@ -11,6 +11,11 @@ export type SoundEffect =
   | 'victory'
   | 'defeat'
   | 'select'
+  | 'game_start'
+  | 'player_join'
+  | 'question_reveal'
+  | 'hover'
+  | 'countdown'
 
 interface SoundState {
   volume: number
@@ -56,6 +61,11 @@ export const soundPaths: Record<ThemeName, Record<SoundEffect, string>> = {
     victory: '/sounds/drrr/victory.mp3',
     defeat: '/sounds/drrr/defeat.mp3',
     select: '/sounds/drrr/select.mp3',
+    game_start: '/sounds/drrr/game_start.mp3',
+    player_join: '/sounds/drrr/player_join.mp3',
+    question_reveal: '/sounds/drrr/question_reveal.mp3',
+    hover: '/sounds/drrr/hover.mp3',
+    countdown: '/sounds/drrr/countdown.mp3',
   },
   retro: {
     correct: '/sounds/retro/correct.mp3',
@@ -66,6 +76,11 @@ export const soundPaths: Record<ThemeName, Record<SoundEffect, string>> = {
     victory: '/sounds/retro/victory.mp3',
     defeat: '/sounds/retro/defeat.mp3',
     select: '/sounds/retro/select.mp3',
+    game_start: '/sounds/retro/game_start.mp3',
+    player_join: '/sounds/retro/player_join.mp3',
+    question_reveal: '/sounds/retro/question_reveal.mp3',
+    hover: '/sounds/retro/hover.mp3',
+    countdown: '/sounds/retro/countdown.mp3',
   },
   minimal: {
     correct: '/sounds/minimal/correct.mp3',
@@ -76,6 +91,11 @@ export const soundPaths: Record<ThemeName, Record<SoundEffect, string>> = {
     victory: '/sounds/minimal/victory.mp3',
     defeat: '/sounds/minimal/defeat.mp3',
     select: '/sounds/minimal/select.mp3',
+    game_start: '/sounds/minimal/game_start.mp3',
+    player_join: '/sounds/minimal/player_join.mp3',
+    question_reveal: '/sounds/minimal/question_reveal.mp3',
+    hover: '/sounds/minimal/hover.mp3',
+    countdown: '/sounds/minimal/countdown.mp3',
   },
   rgb: {
     correct: '/sounds/rgb/correct.mp3',
@@ -86,6 +106,11 @@ export const soundPaths: Record<ThemeName, Record<SoundEffect, string>> = {
     victory: '/sounds/rgb/victory.mp3',
     defeat: '/sounds/rgb/defeat.mp3',
     select: '/sounds/rgb/select.mp3',
+    game_start: '/sounds/rgb/game_start.mp3',
+    player_join: '/sounds/rgb/player_join.mp3',
+    question_reveal: '/sounds/rgb/question_reveal.mp3',
+    hover: '/sounds/rgb/hover.mp3',
+    countdown: '/sounds/rgb/countdown.mp3',
   },
   anime: {
     correct: '/sounds/anime/correct.mp3',
@@ -96,6 +121,11 @@ export const soundPaths: Record<ThemeName, Record<SoundEffect, string>> = {
     victory: '/sounds/anime/victory.mp3',
     defeat: '/sounds/anime/defeat.mp3',
     select: '/sounds/anime/select.mp3',
+    game_start: '/sounds/anime/game_start.mp3',
+    player_join: '/sounds/anime/player_join.mp3',
+    question_reveal: '/sounds/anime/question_reveal.mp3',
+    hover: '/sounds/anime/hover.mp3',
+    countdown: '/sounds/anime/countdown.mp3',
   },
 }
 
@@ -110,4 +140,9 @@ export const fallbackSoundConfigs: Record<SoundEffect, { frequency: number; dura
   victory: { frequency: 523, duration: 0.5, type: 'sine' },
   defeat: { frequency: 196, duration: 0.5, type: 'sine' },
   select: { frequency: 600, duration: 0.08, type: 'sine' },
+  game_start: { frequency: 440, duration: 0.4, type: 'sine' },
+  player_join: { frequency: 520, duration: 0.12, type: 'sine' },
+  question_reveal: { frequency: 700, duration: 0.2, type: 'triangle' },
+  hover: { frequency: 400, duration: 0.03, type: 'sine' },
+  countdown: { frequency: 600, duration: 0.15, type: 'square' },
 }