feat: add db schema, init, and vitest config

data-pipeline/db/index.ts

@@ -0,0 +1,24 @@
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import Database from "better-sqlite3";
+
+// ── Paths ─────────────────────────────────────────────────────────────────────
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+const DB_PATH = path.join(__dirname, "pipeline.db");
+
+// ── Types ─────────────────────────────────────────────────────────────────────
+
+export type Db = InstanceType<typeof Database>;
+
+// ── Open ──────────────────────────────────────────────────────────────────────
+
+export function openDb(): Db {
+  const db = new Database(DB_PATH);
+
+  db.pragma("journal_mode = WAL");
+  db.pragma("foreign_keys = ON");
+
+  return db;
+}