Fix architecture and README accuracy findings from review

- Topology: show the port mapping host 8090 -> container 8080, and note
  that searxng is internal to the compose network with no published port.
- Backend: logging is log/slog JSON.
- Scheduler: only the household-configurable times live in
  household_settings; week_rollover and the ai_runs purge are fixed.
- README: state the Node.js floor required by the committed lockfile.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -13,7 +13,9 @@ single Go service with the React PWA embedded in the binary.
 
 ## Quick start
 
-Requirements: Go 1.25 and Node.js 22.
+Requirements: Go 1.25 and Node.js 22.22.2 or newer (or 24.15 or newer).
+Vite and Vitest need at least 22.12; jsdom in the committed lockfile needs
+22.22.2 on the 22 line.
 
 ```sh
 (cd web && npm ci)