blog: add fixing DoH tail latency post + blog infrastructure

New post on reqwest HTTP/2 window tuning and request hedging
(Dean & Barroso's "The Tail at Scale" applied to DNS forwarding).
Covers DoH forwarding p99 improvement and cold recursive
resolution from 2.3s to 538ms.

Also adds blog build infrastructure: index generation script,
draft preview server, hero metrics/before-after CSS, and
normalizes date format across existing posts.

scripts/serve-site.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+PORT="${1:-9000}"
+
+if [[ "${1:-}" == "--drafts" ]] || [[ "${2:-}" == "--drafts" ]]; then
+  PORT="${PORT//--drafts/9000}"  # default port if --drafts was first arg
+  make blog-drafts
+else
+  make blog
+fi
+
+echo "Serving site at http://localhost:$PORT"
+cd site && python3 -m http.server "$PORT"