Add Drizzle + Postgres setup (task 03)

drizzle-orm + postgres driver + drizzle-kit wired up. Core schema declares
users, households, and household_members. docker-compose.dev.yaml runs
Postgres 16 locally. Initial migration generated and verified applied.

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

drizzle.config.ts

@@ -0,0 +1,10 @@
+import { defineConfig } from "drizzle-kit";
+
+export default defineConfig({
+  dialect: "postgresql",
+  schema: "./src/modules/**/schema.ts",
+  out: "./drizzle",
+  dbCredentials: {
+    url: process.env["DATABASE_URL"]!,
+  },
+});