feat: Prisma schema, migrations en seed voor auth en audit-log

- Models: User, Session, FlowRun, FlowStep met FlowStatus enum
- prisma.config.ts met DATABASE_URL via @prisma/adapter-pg (Prisma 7 API)
- Initiële migratie applied op ops_dashboard database
- Seed-script voor 1 user via SEED_USER_EMAIL/SEED_USER_PASSWORD env-vars
- lib/prisma.ts als gedeelde singleton client voor Next.js

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

prisma/migrations/20260513150226_init/migration.sql

@@ -0,0 +1,67 @@
+-- CreateEnum
+CREATE TYPE "FlowStatus" AS ENUM ('pending', 'running', 'success', 'failed', 'cancelled');
+
+-- CreateTable
+CREATE TABLE "User" (
+    "id" TEXT NOT NULL,
+    "email" TEXT NOT NULL,
+    "pwd_hash" TEXT NOT NULL,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "User_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "Session" (
+    "id" TEXT NOT NULL,
+    "user_id" TEXT NOT NULL,
+    "token_hash" TEXT NOT NULL,
+    "expires_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "Session_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "FlowRun" (
+    "id" TEXT NOT NULL,
+    "user_id" TEXT NOT NULL,
+    "flow_key" TEXT NOT NULL,
+    "status" "FlowStatus" NOT NULL DEFAULT 'pending',
+    "dry_run" BOOLEAN NOT NULL DEFAULT false,
+    "started_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "ended_at" TIMESTAMP(3),
+    "exit_code" INTEGER,
+
+    CONSTRAINT "FlowRun_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "FlowStep" (
+    "id" TEXT NOT NULL,
+    "flow_run_id" TEXT NOT NULL,
+    "step_index" INTEGER NOT NULL,
+    "command_key" TEXT NOT NULL,
+    "args_json" TEXT,
+    "stdout" TEXT,
+    "stderr" TEXT,
+    "exit_code" INTEGER,
+    "started_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "ended_at" TIMESTAMP(3),
+
+    CONSTRAINT "FlowStep_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "User_email_key" ON "User"("email");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "Session_token_hash_key" ON "Session"("token_hash");
+
+-- AddForeignKey
+ALTER TABLE "Session" ADD CONSTRAINT "Session_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "User"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "FlowRun" ADD CONSTRAINT "FlowRun_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "User"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "FlowStep" ADD CONSTRAINT "FlowStep_flow_run_id_fkey" FOREIGN KEY ("flow_run_id") REFERENCES "FlowRun"("id") ON DELETE CASCADE ON UPDATE CASCADE;