feat(db): @mosaic/db — Drizzle schema, PG connection, migrations (#67)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/db/src/client.ts

@@ -0,0 +1,18 @@
+import { drizzle, type PostgresJsDatabase } from 'drizzle-orm/postgres-js';
+import postgres from 'postgres';
+import * as schema from './schema.js';
+import { DEFAULT_DATABASE_URL } from './defaults.js';
+
+export type Db = PostgresJsDatabase<typeof schema>;
+
+export interface DbHandle {
+  db: Db;
+  close: () => Promise<void>;
+}
+
+export function createDb(url?: string): DbHandle {
+  const connectionString = url ?? process.env['DATABASE_URL'] ?? DEFAULT_DATABASE_URL;
+  const sql = postgres(connectionString);
+  const db = drizzle(sql, { schema });
+  return { db, close: () => sql.end() };
+}