[node] begin the great typescript rewrite

nodejs/database/agents.ts

@@ -0,0 +1,20 @@
+import { Agent } from '../model/agent.ts';
+import db from './db.js';
+
+const addAgentStatement = db.prepare(`INSERT INTO agents(data) VALUES (json(?));`);
+const getAgentStatement = db.prepare(`SELECT data FROM agents;`);
+const setAgentStatement = db.prepare(`UPDATE agents SET data = json(?);`);
+
+export function addAgent(agent: Agent) {
+	addAgentStatement.run(JSON.stringify(agent));
+}
+
+export function getAgent(): Agent|null {
+	const data = getAgentStatement.get() as {data: string}|undefined;
+	if (!data) return null;
+	return JSON.parse(data.data);
+}
+
+export function setAgent(agent: Agent) {
+	setAgentStatement.run(JSON.stringify(agent));
+}