feat: remove dev_session, add Drizzle schema + RLS + real auth

BREAKING: dev_session cookie bypass removed. Admin access now requires
a real Auth.js v5 session (Google OAuth in production). Provision users
by inserting into users + tenant_users tables.

New in this commit:
- db/migrations/0001_init.sql: 18-table SaaS schema with RLS (tenants,
  users, tenant_users, plans, add_ons, subscriptions, tenant_add_ons,
  products, product_images, stops, customers, orders, order_items,
  brand_settings, email_templates, campaigns, files, audit_log)
- db/schema/: Drizzle TypeScript mirror of every table
- db/client.ts: withTenant() / withPlatformAdmin() query wrappers that
  set Postgres GUCs (app.current_tenant_id, app.platform_admin) for
  RLS enforcement. Never query a tenant-scoped table without one.
- db/seed.ts: seeds 3 plans, 6 add-ons, 2 tenants (Tuxedo, Indian River
  Direct), brand_settings, sample products/stops/customers
- scripts/migrate.js: applies migrations in lexical order with tracking
- scripts/db-reset.js: drops + recreates DB, runs migrate + seed
- DATABASE_URL now uses rc_app (non-superuser, NOBYPASSRLS). RLS is
  enforced even for the app user. DATABASE_ADMIN_URL for migrations.
- src/lib/admin-permissions.ts: getAdminUser() reads Auth.js session,
  looks up user + tenant in Postgres. brand_id kept as alias for
  backward compat.
- src/middleware.ts: Auth.js-only route protection, dev_session gone
- src/app/login/LoginClient.tsx: Google OAuth only, no demo mode
- src/components/admin/AdminSidebar.tsx + AdminHeader.tsx: signOutAction
  replaces supabase signout
- @/db/* path aliases in tsconfig.json + vitest.config.ts
- drizzle.config.ts added
- db/auth_schema.sql removed (was a stub; replaced by real schema)
- src/app/api/dev-login/route.ts deleted
- tests: updated to remove dev_session coverage

db/client.ts

@@ -0,0 +1,134 @@
+/**
+ * Drizzle client + tenant-scoped query helper.
+ *
+ * The app connects to Postgres directly via the `pg` driver. Drizzle sits
+ * on top, providing typed queries. The `withTenant` wrapper is the only
+ * sanctioned way to run a tenant-scoped query — it sets the
+ * `app.current_tenant_id` GUC transaction-locally, and the database's
+ * RLS policies enforce tenant isolation even if application code forgets
+ * a `WHERE tenant_id = $1`.
+ *
+ * Usage (read):
+ *   const products = await withTenant(tenantId, (db) =>
+ *     db.select().from(productsTable).where(eq(productsTable.active, true)),
+ *   );
+ *
+ * Usage (platform admin — sees all tenants):
+ *   const allTenants = await withPlatformAdmin((db) =>
+ *     db.select().from(tenantsTable),
+ *   );
+ *
+ * Usage (no tenant — for the rare case the query isn't tenant-scoped):
+ *   const plans = await withDb((db) => db.select().from(plansTable));
+ */
+
+import "server-only";
+import { Pool, type PoolClient } from "pg";
+import { drizzle, type NodePgDatabase } from "drizzle-orm/node-postgres";
+import * as schema from "./schema";
+
+type Schema = typeof schema;
+export type Db = NodePgDatabase<Schema>;
+
+let _pool: Pool | null = null;
+
+function getPool(): Pool {
+  if (_pool) return _pool;
+  const connectionString = process.env.DATABASE_URL;
+  if (!connectionString) {
+    throw new Error(
+      "DATABASE_URL is not set. Add it to .env.local (see .env.example).",
+    );
+  }
+  _pool = new Pool({
+    connectionString,
+    max: parseInt(process.env.PG_POOL_MAX ?? "10", 10),
+    idleTimeoutMillis: parseInt(process.env.PG_POOL_IDLE_MS ?? "30000", 10),
+    connectionTimeoutMillis: parseInt(
+      process.env.PG_POOL_CONN_TIMEOUT_MS ?? "10000",
+      10,
+    ),
+    allowExitOnIdle: false,
+  });
+  _pool.on("error", (err) => {
+    console.error("[db] idle client error", err);
+  });
+  return _pool;
+}
+
+/**
+ * Run `fn` with a Drizzle client. No tenant context is set — the caller
+ * is responsible for RLS bypass (e.g. for the `plans` and `add_ons` tables,
+ * which are not tenant-scoped). For tenant-scoped reads, prefer
+ * `withTenant` or `withPlatformAdmin`.
+ */
+export async function withDb<T>(fn: (db: Db) => Promise<T>): Promise<T> {
+  const client = await getPool().connect();
+  try {
+    const db = drizzle(client, { schema });
+    return await fn(db);
+  } finally {
+    client.release();
+  }
+}
+
+/**
+ * Run `fn` inside a transaction with the current tenant id set as a
+ * transaction-local GUC. RLS policies on tenant-scoped tables will allow
+ * reads/writes only for rows where `tenant_id` matches. Pass `null` to
+ * fail open (don't set the GUC) — only useful for the migrations
+ * themselves, never for app code.
+ */
+export async function withTenant<T>(
+  tenantId: string,
+  fn: (db: Db) => Promise<T>,
+): Promise<T> {
+  return runInTransaction(async (client) => {
+    // set_config(setting, value, is_local) — is_local=true makes it
+    // transaction-local so it auto-resets at COMMIT/ROLLBACK and never
+    // leaks across pooled connections.
+    await client.query("SELECT set_config('app.current_tenant_id', $1, true)", [
+      tenantId,
+    ]);
+    await client.query("SELECT set_config('app.platform_admin', 'false', true)");
+    const db = drizzle(client, { schema });
+    return fn(db);
+  });
+}
+
+/**
+ * Run `fn` as platform admin. RLS policies permit access to all tenants.
+ * Use sparingly — typically only in the /admin/platform routes.
+ */
+export async function withPlatformAdmin<T>(
+  fn: (db: Db) => Promise<T>,
+): Promise<T> {
+  return runInTransaction(async (client) => {
+    await client.query("SELECT set_config('app.platform_admin', 'true', true)");
+    const db = drizzle(client, { schema });
+    return fn(db);
+  });
+}
+
+async function runInTransaction<T>(
+  fn: (client: PoolClient) => Promise<T>,
+): Promise<T> {
+  const client = await getPool().connect();
+  try {
+    await client.query("BEGIN");
+    const result = await fn(client);
+    await client.query("COMMIT");
+    return result;
+  } catch (err) {
+    try {
+      await client.query("ROLLBACK");
+    } catch {
+      // ignore secondary rollback failure
+    }
+    throw err;
+  } finally {
+    client.release();
+  }
+}
+
+export { schema };