feat(db): add Better Auth tables (Session, Account, Verification)

- User extended with emailVerified, name, image (Better Auth fields)
- Session: signed session tokens with expiry, ip and user agent
- Account: credential rows for email+password (provider 'credential') and
  OAuth providers (e.g. Google) — password hash stored on the credential row
- Verification: single-use tokens for email verification, password reset,
  and magic links
- Re-export new types from @ketopath/db

Migration 20260429104721_add_auth_tables run against local Postgres.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/db/prisma/migrations/20260429104721_add_auth_tables/migration.sql

@@ -0,0 +1,64 @@
+-- AlterTable
+ALTER TABLE "users" ADD COLUMN     "email_verified" BOOLEAN NOT NULL DEFAULT false,
+ADD COLUMN     "image" TEXT,
+ADD COLUMN     "name" TEXT;
+
+-- CreateTable
+CREATE TABLE "sessions" (
+    "id" TEXT NOT NULL,
+    "user_id" TEXT NOT NULL,
+    "token" TEXT NOT NULL,
+    "expires_at" TIMESTAMP(3) NOT NULL,
+    "ip_address" TEXT,
+    "user_agent" TEXT,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "sessions_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "accounts" (
+    "id" TEXT NOT NULL,
+    "user_id" TEXT NOT NULL,
+    "account_id" TEXT NOT NULL,
+    "provider_id" TEXT NOT NULL,
+    "access_token" TEXT,
+    "refresh_token" TEXT,
+    "id_token" TEXT,
+    "access_token_expires_at" TIMESTAMP(3),
+    "refresh_token_expires_at" TIMESTAMP(3),
+    "scope" TEXT,
+    "password" TEXT,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "accounts_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "verifications" (
+    "id" TEXT NOT NULL,
+    "identifier" TEXT NOT NULL,
+    "value" TEXT NOT NULL,
+    "expires_at" TIMESTAMP(3) NOT NULL,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "verifications_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "sessions_token_key" ON "sessions"("token");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "accounts_provider_id_account_id_key" ON "accounts"("provider_id", "account_id");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "verifications_identifier_value_key" ON "verifications"("identifier", "value");
+
+-- AddForeignKey
+ALTER TABLE "sessions" ADD CONSTRAINT "sessions_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "users"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "accounts" ADD CONSTRAINT "accounts_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "users"("id") ON DELETE CASCADE ON UPDATE CASCADE;