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/k3s/kustomization.yaml

@@ -37,6 +37,9 @@ images:
   - name: geo-rankly/tenant-api
     newName: geo-rankly/tenant-api
     newTag: latest
+  - name: geo-rankly/browser-fetch
+    newName: geo-rankly/browser-fetch
+    newTag: latest
   - name: geo-rankly/worker-generate
     newName: geo-rankly/worker-generate
     newTag: latest