docs: add blog post on nf_conntrack overflow with Docker UDP tracker

Documents the mechanism, diagnosis, fix, and alternatives for the
nf_conntrack table exhaustion problem that caused UDP tracker downtime
on both the DigitalOcean and Hetzner demos.

Covers:
- How Docker bridge DNAT forces connection tracking for UDP
- The three-parameter sysctl fix (nf_conntrack_max, udp_timeout,
  udp_timeout_stream) and module pre-load for reboot persistence
- Hash table sizing (nf_conntrack_buckets / hashsize)
- Alternative approaches: host networking, NOTRACK, macvlan
- Real-world NOTRACK failure on torrust/torrust-demo#72
- Monitoring commands (conntrack -S, early_drop, 80% alert)
- Links to independent documentation (Aquatic tracker guide)

Fixes confirmed: post-fix UDP uptime 99.9% on Hetzner demo.

Author: josecelano

src/routes/blog/nf-conntrack-overflow-docker-udp-tracker/+page.server.ts

@@ -0,0 +1,14 @@
+import { getMetadata } from '$lib/data/metadata';
+import type { PageServerLoad } from './$types';
+
+export const load: PageServerLoad = async ({ url }) => {
+	const slug = url.pathname.split('/').filter(Boolean).pop();
+	if (!slug) throw new Error('Slug could not be determined.');
+
+	const metadata = await getMetadata();
+	const currentPost = metadata.find((post) => post.slug === slug);
+
+	if (!currentPost) throw new Error(`Post not found: ${slug}`);
+
+	return { currentPost, allPosts: metadata };
+};