feat(speedtest): full speedtest-tracker-style automation (2.9.0)

Switch worker to the Ookla CLI (jitter, packet loss, server, ISP,
shareable result URL, bytes). Migration 028 enriches speedtest_results
+ adds a generic app_settings store. New /speedtest page: KPIs,
throughput + latency charts, window stats, configurable schedule
(reschedulable cron) & low-speed alert threshold, history table.
SV card gains ping/jitter + a link through to the page.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "void-server",
-  "version": "2.8.0",
+  "version": "2.9.0",
   "type": "module",
   "private": true,
   "scripts": {