perf: add bans.user_id index, Redis cache layer, rate-limit improvements, radio contest/giveaway columns, and tests

- Add DB index on bans.user_id to speed up per-request ban lookups (migration 0008)
- Replace in-process rate limiter with Redis-backed implementation with in-memory fallback
- Add Redis caching layer for site settings with TTL invalidation (migration 0009)
- Add rate limiting to resetPassword to prevent token brute-force attacks
- Update all rateLimit callers to await the now-async function
- Flesh out RadioContests and RadioGiveaways models with title, description, prize, date, and winner columns
- Update radio contest/giveaway pages to display new fields
- Add tests for rate limiter (4 tests) and password-reset actions (3 tests)
- Add REDIS_URL environment variable (optional, falls back to in-memory)

prisma/schema.prisma

@@ -92,6 +92,7 @@ model Ban {
   type        bans_type @default(account)
   cfhTopic    Int       @default(-1) @map("cfh_topic")
 
+  @@index([userId])
   @@map("bans")
 }
 
@@ -2121,17 +2122,35 @@ model RadioHistory {
 }
 
 model RadioContests {
-  id        BigInt    @id @default(autoincrement()) @db.UnsignedBigInt
-  createdAt DateTime? @map("created_at") @db.Timestamp(0)
-  updatedAt DateTime? @map("updated_at") @db.Timestamp(0)
+  id          BigInt    @id @default(autoincrement()) @db.UnsignedBigInt
+  title       String    @db.VarChar(255)
+  description String?   @db.Text
+  prize       String?   @db.VarChar(255)
+  startDate   DateTime? @map("start_date") @db.Timestamp(0)
+  endDate     DateTime? @map("end_date") @db.Timestamp(0)
+  winnerId    BigInt?   @map("winner_id") @db.UnsignedBigInt
+  isActive    Boolean   @default(true) @map("is_active")
+  createdBy   BigInt?   @map("created_by") @db.UnsignedBigInt
+  createdAt   DateTime? @map("created_at") @db.Timestamp(0)
+  updatedAt   DateTime? @map("updated_at") @db.Timestamp(0)
 
   @@map("radio_contests")
 }
 
 model RadioGiveaways {
-  id        BigInt    @id @default(autoincrement()) @db.UnsignedBigInt
-  createdAt DateTime? @map("created_at") @db.Timestamp(0)
-  updatedAt DateTime? @map("updated_at") @db.Timestamp(0)
+  id          BigInt    @id @default(autoincrement()) @db.UnsignedBigInt
+  title       String    @db.VarChar(255)
+  description String?   @db.Text
+  prize       String?   @db.VarChar(255)
+  prizeAmount Int       @default(0) @map("prize_amount")
+  prizeCurrency String? @map("prize_currency") @db.VarChar(50)
+  startDate   DateTime? @map("start_date") @db.Timestamp(0)
+  endDate     DateTime? @map("end_date") @db.Timestamp(0)
+  winnerId    BigInt?   @map("winner_id") @db.UnsignedBigInt
+  isActive    Boolean   @default(true) @map("is_active")
+  createdBy   BigInt?   @map("created_by") @db.UnsignedBigInt
+  createdAt   DateTime? @map("created_at") @db.Timestamp(0)
+  updatedAt   DateTime? @map("updated_at") @db.Timestamp(0)
 
   @@map("radio_giveaways")
 }