The Cuckoo Escapement: field report, kernel patch, dashboard

What the Raspberry Pi time-server guides get wrong on a Pi 4, with the
measurements. The headline artifact is a four-line pps-gpio patch: PREEMPT_RT
force-threads IRQ handlers, and pps-gpio takes its timestamp inside its handler,
so the realtime kernel puts a scheduler between the electrical edge and the
clock. IRQF_NO_THREAD takes RMS offset from 2468 ns to 199 ns.

- kernel/     the patch
- dashboard/  live status page (position hidden by default)
- docs-site/  the write-up (Astro/Starlight, brass, no tutorial section)

docs-site/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "cuckoo-escapement-docs",
+  "type": "module",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "astro dev --host 0.0.0.0",
+    "build": "astro build",
+    "preview": "astro preview --host 0.0.0.0",
+    "astro": "astro"
+  },
+  "dependencies": {
+    "@astrojs/mdx": "^5.0.4",
+    "@astrojs/sitemap": "^3.7.2",
+    "@astrojs/starlight": "^0.39.2",
+    "astro": "^6.3.1",
+    "sharp": "^0.34.0",
+    "starlight-links-validator": "^0.24.0"
+  }
+}