feat(01-01): install Drizzle ORM, postgres-js, and configure DB client

- drizzle-orm@0.45.2 + postgres@3.4.9 installed (postgres-js driver)
- drizzle-kit@0.31.10 installed as dev dependency
- nanoid@5, zod@4, react-hook-form, @hookform/resolvers installed
- src/db/index.ts: Drizzle client initialized with postgres-js driver
- drizzle.config.ts: configured for postgresql dialect + src/db/schema.ts
- .env.example: added as public template (no secrets)
- .gitignore: allow .env.example while blocking all other .env* files

src/db/index.ts

@@ -0,0 +1,10 @@
+import { drizzle } from "drizzle-orm/postgres-js";
+import postgres from "postgres";
+
+if (!process.env.DATABASE_URL) {
+  throw new Error("DATABASE_URL env var is required");
+}
+
+const client = postgres(process.env.DATABASE_URL);
+
+export const db = drizzle(client);