WP-02: encrypted settings, SMTP mail, job runner and cron scheduler

AES-256-GCM secret storage keyed by MASTER_KEY, SMTP settings with test mail
(lettre), persisted job runs with log and status, JobRunner with per-kind
concurrency guard, 6-field cron schedules with defaults, scheduler loop.
Settings and Jobs pages in the UI. FAKE_HOST mode for dev machines.

Tests: 30 application, 8 infrastructure, 23 API, 16 Vitest, 6 Playwright.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

deploy/deploy-test.sh

@@ -27,6 +27,7 @@ if ! ssh "$HOST" "test -f $DIR/.env"; then
   ssh "$HOST" "umask 077; cat > $DIR/.env" <<ENV
 DATABASE_URL=sqlite://$DIR/data/monitoring.db?mode=rwc
 JWT_SECRET=$(openssl rand -hex 32)
+MASTER_KEY=$(openssl rand -hex 32)
 BIND=0.0.0.0:$PORT
 BOOTSTRAP_ADMIN_EMAIL=admin@softvisor.de
 BOOTSTRAP_ADMIN_PASSWORD=$ADMIN_PW
@@ -37,6 +38,9 @@ ENV
   echo "Bootstrap admin: admin@softvisor.de / $ADMIN_PW  (change it after first login)"
 fi
 
+# add settings introduced later to an existing .env
+ssh "$HOST" "grep -q '^MASTER_KEY=' $DIR/.env || echo MASTER_KEY=$(openssl rand -hex 32) >> $DIR/.env"
+
 echo "== systemd"
 ssh "$HOST" "cat > /etc/systemd/system/monitoring.service" <<UNIT
 [Unit]