feat: add database schema and connection pool

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

vitest.config.ts

@@ -0,0 +1,14 @@
+import { defineConfig } from 'vitest/config';
+import path from 'path';
+
+export default defineConfig({
+	test: {
+		include: ['tests/unit/**/*.test.ts'],
+		exclude: ['tests/e2e/**'],
+	},
+	resolve: {
+		alias: {
+			$lib: path.resolve('./src/lib')
+		}
+	}
+});