Add secure Bird gateway for Pleno Control Plane (#332)

Add the Bird Control Plane gateway, signed webhook ingestion, policy-gated writes, fail-closed production auto-activation, and RSA-OAEP bootstrap credential flow.

scripts/bird-control-plane-auto-activate.php

@@ -0,0 +1,28 @@
+#!/usr/bin/env php
+<?php
+
+if (PHP_SAPI !== 'cli') {
+    exit(2);
+}
+
+$appDirectory = __DIR__ . '/../services/nginx/app';
+if (!is_file($appDirectory . '/config.php')) {
+    $appDirectory = dirname(__DIR__);
+}
+define('WD', $appDirectory);
+require_once WD . '/vendor/autoload.php';
+require_once WD . '/config.php';
+require_once WD . '/classes/db.php';
+require_once WD . '/modules/bird/classes/bird_control_plane_auto_activation.php';
+
+try {
+    $status = (new \bird\classes\bird_control_plane_auto_activation(
+        \classes\db::getPDO()
+    ))->run();
+    fwrite(STDOUT, json_encode($status, JSON_UNESCAPED_SLASHES) . PHP_EOL);
+    exit(($status['ready'] ?? false) === true ? 0 : 1);
+} catch (Throwable $throwable) {
+    error_log('[bird-control-plane-auto-activate] Failed: ' . get_class($throwable));
+    fwrite(STDOUT, '{"ready":false,"errorCode":"bird_auto_activation_failed"}' . PHP_EOL);
+    exit(1);
+}