feat: Implement feature flag system with helpers, service, and loader

- Added feature flag helpers and decorators for easy usage in commands.
- Created a feature flag service for managing flags, including initialization, caching, and evaluation strategies.
- Implemented a loader to initialize the feature flag service on bot startup.
- Defined types for feature flags, including configurations, contexts, evaluations, and statistics.
- Provided examples of feature flag usage in commands, demonstrating various patterns such as A/B testing, gradual rollouts, and access control.

prisma/schema.prisma

@@ -1052,3 +1052,40 @@ model DeathLog {
   @@index([userId, guildId])
   @@index([createdAt])
 }
+
+/**
+ * -----------------------------------------------------------------------------
+ * Sistema de Feature Flags
+ * -----------------------------------------------------------------------------
+ * Control de features para rollouts progresivos, A/B testing y toggles
+ * Permite activar/desactivar funcionalidades sin deployar código
+ */
+model FeatureFlag {
+  id   String @id @default(cuid())
+  name String @unique
+
+  description String?
+  status      String  @default("disabled") // enabled|disabled|rollout|maintenance
+
+  // Nivel de aplicación: global, guild, user, channel
+  target String @default("global")
+
+  // Estrategia de rollout (para status = rollout)
+  rolloutStrategy String? // percentage|whitelist|blacklist|gradual|random
+
+  // Configuración de la estrategia (JSON)
+  rolloutConfig String? // JSON serializado
+
+  // Fechas de inicio/fin
+  startDate DateTime?
+  endDate   DateTime?
+
+  // Metadata adicional
+  metadata String? // JSON serializado
+
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  @@index([status])
+  @@index([target])
+}