feat: add prompt service (#6241)

fix CLOUD-19

packages/backend/server/migrations/20240321065017_ai_prompts/migration.sql

@@ -0,0 +1,16 @@
+-- CreateEnum
+CREATE TYPE "AiPromptRole" AS ENUM ('system', 'assistant', 'user');
+
+-- CreateTable
+CREATE TABLE "ai_prompts" (
+    "id" VARCHAR NOT NULL,
+    "name" VARCHAR(20) NOT NULL,
+    "idx" INTEGER NOT NULL,
+    "role" "AiPromptRole" NOT NULL,
+    "content" TEXT NOT NULL,
+    "created_at" TIMESTAMPTZ(6) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT "ai_prompts_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "ai_prompts_name_idx_key" ON "ai_prompts"("name", "idx");