fix(deps): pin Node 24.22.1 for the October 21, 2026 security release

Node.js 24.14.0 carries CVE-2026-111497 ("Node2Shell"), an out-of-bounds
write in the bundled Brotli decoder that can lead to remote code
execution, plus several high-severity DNS, TLS and URL-parsing fixes.
24.22.1 is the first patched 24.x release.

- Dockerfile: node:24.22.1-slim, digest re-pinned to the multi-arch index
- CI: 24.22.1 in the verify matrix and the other two jobs; the
  allocation-gate requirement now keys on 24.22.1
- Docs: contributor setup and the dependency baseline name 24.22.1

The engines floor and the setup doctor are unchanged.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

Dockerfile

@@ -4,7 +4,7 @@
 # proxies (ADS-B, AIS, Overpass, OpenAI Realtime, ...) as middleware, so there
 # is nothing else to containerise. See compose.yaml for the usual entry point.
 # Same Node as CI (package.json engines, .github/workflows), pinned by digest.
-FROM node:24.14.0-slim@sha256:d8e448a56fc63242f70026718378bd4b00f8c82e78d20eefb199224a4d8e33d8
+FROM node:24.22.1-slim@sha256:be8204d4bd327363357f532187b752ff62759c31bedf98e9e18fc08c9cbd605c
 
 # Puppeteer is only used by the QA scripts; skip its ~150MB Chromium download.
 ENV PUPPETEER_SKIP_DOWNLOAD=1