feat: port scenario 903 select-pool flow

packages/infra/prisma/game.prisma

@@ -198,6 +198,19 @@ model General {
   @@map("general")
 }
 
+model SelectPoolEntry {
+  id            Int       @id @default(autoincrement())
+  uniqueName    String    @unique @map("unique_name") @db.VarChar(20)
+  ownerUserId   String?   @map("owner_user_id")
+  generalId     Int?      @unique @map("general_id")
+  reservedUntil DateTime? @map("reserved_until")
+  info          Json
+
+  @@index([ownerUserId])
+  @@index([reservedUntil, generalId])
+  @@map("select_pool")
+}
+
 model GeneralAccessLog {
   id                Int       @id @default(autoincrement())
   generalId         Int       @unique @map("general_id")

packages/infra/prisma/migrations/20260730002000_add_select_pool/migration.sql

@@ -0,0 +1,17 @@
+CREATE TABLE "select_pool" (
+    "id" SERIAL PRIMARY KEY,
+    "unique_name" VARCHAR(20) NOT NULL,
+    "owner_user_id" TEXT,
+    "general_id" INTEGER,
+    "reserved_until" TIMESTAMP(3),
+    "info" JSONB NOT NULL
+);
+
+CREATE UNIQUE INDEX "select_pool_unique_name_key"
+    ON "select_pool"("unique_name");
+CREATE UNIQUE INDEX "select_pool_general_id_key"
+    ON "select_pool"("general_id");
+CREATE INDEX "select_pool_owner_user_id_idx"
+    ON "select_pool"("owner_user_id");
+CREATE INDEX "select_pool_reserved_until_general_id_idx"
+    ON "select_pool"("reserved_until", "general_id");