Runner: Proxy härten (R13 Listen-Adressen, Hop-by-hop, Upgrade-Race, Touch, Timeout)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

runner/src/config.js

@@ -8,6 +8,7 @@ export function loadConfig(env = process.env) {
     previewsRoot: env.PREVIEWS_ROOT || '/var/www/previews',
     workRoot: env.RUNNER_WORK_ROOT || '/srv/webklar-preview-runner/work',
     cacheRoot: env.RUNNER_CACHE_ROOT || '/srv/webklar-preview-runner/cache',
+    sandboxSubnet: env.PREVIEW_SANDBOX_SUBNET || '172.30.0.0/24',
     apiPort: 8080,
     proxyPort: 8081,
     minFreeBytes: 1.5 * 1024 ** 3,