feat(browser-fetch): add lightpanda-backed fetch service and knowledge URL fallback

Adds a new browser-fetch microservice that wraps Lightpanda for rendering
JS-heavy pages, and wires it into the knowledge URL parser as a fallback
when the upstream link reader returns 403/429/5xx for an allow-listed
domain (e.g. zhuanlan.zhihu.com). Includes config/env plumbing, hot-reload
diff support, and full deploy assets (Dockerfile target, docker-compose,
k3s manifests, image-build/package scripts).

deploy/.env.example

@@ -14,6 +14,7 @@ JWT_SECRET=geo-web-Aa123456-change-me-in-production
 OPS_JWT_SECRET=geo-ops-Aa123456-change-me-in-production
 OPS_DEFAULT_ADMIN_PASSWORD=Aa123456
 SCHEDULER_INTERNAL_METRICS_TOKEN=geo-scheduler-Aa123456-change-me-in-production
+BROWSER_FETCH_TOKEN=geo-browser-fetch-Aa123456-change-me-in-production
 POSTGRES_PASSWORD=geo_dev
 
 # ─── Optional: MinIO credentials ─────────────────────────────────────────────