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>

lib/db/repos/app_settings.js

@@ -0,0 +1,17 @@
+import { pool } from '../pool.js';
+
+// Generic owner-scoped key→jsonb settings store. Used by the speedtest schedule
+// and (later) the theming panel. Keep values small + JSON-serialisable.
+export async function get(key, fallback = null) {
+  const { rows } = await pool.query(`SELECT value FROM app_settings WHERE key = $1`, [key]);
+  return rows[0] ? rows[0].value : fallback;
+}
+
+export async function set(key, value) {
+  const { rows } = await pool.query(
+    `INSERT INTO app_settings (key, value, updated_at) VALUES ($1, $2::jsonb, now())
+     ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = now()
+     RETURNING value`,
+    [key, JSON.stringify(value)]);
+  return rows[0].value;
+}