add healthz, docker fixes, minor readme tweaks

src/routes/healthz/+server.ts

@@ -0,0 +1,16 @@
+// src/routes/healthz/+server.ts
+import { json } from '@sveltejs/kit';
+import { drizzleQuery } from '$lib/database/db';
+import { sql } from 'drizzle-orm';
+
+export async function GET() {
+	try {
+		await drizzleQuery.execute(sql`select 1`);
+		return json({ ok: true }, { headers: { 'cache-control': 'no-store' } });
+	} catch (err) {
+		return json(
+			{ ok: false, error: (err as Error)?.message ?? 'DB unavailable' },
+			{ status: 503, headers: { 'cache-control': 'no-store' } }
+		);
+	}
+}