Add f7push v0.1: FCM device registry and push API for F7cloud.

Portable occ-based config, OCS endpoints for APK registration, notification relay, and server-side push dispatch.

scripts/generate-secret.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# Print or set f7push API secret on this F7cloud server.
+set -euo pipefail
+cd /var/www/f7cloud
+if [[ "${1:-}" == "--regenerate" ]]; then
+  SECRET=$(openssl rand -base64 36 | tr -d '/+=' | head -c 48)
+  sudo -u www-data php occ config:app:set f7push api_secret --value="$SECRET"
+  echo "$SECRET"
+else
+  sudo -u www-data php occ config:app:get f7push api_secret 2>/dev/null || true
+  echo "(If empty, call POST /push once or run with --regenerate)"
+fi