docs(link): 写明内部面明文 HTTP 的单节点前提与放行范围，修正配置模板里的内部面地址

docs/troubleshooting.md

@@ -374,6 +374,16 @@ the no-Zero-Trust face is never exposed on a node. On the control-plane node the
 break-glass console reaches it by resolving that Service's ClusterIP and dialing
 `:8081`.
 
+The face speaks plain HTTP, and the tokens cross it in the clear. That holds up because
+no hop leaves the node: the proxy runs on the node and dials the ClusterIP, and the
+login pod and the build Job are pods on the same node, so reading the traffic takes root
+there, which also reads the tokens from disk. Pods reach the face only where a policy
+opens it: `felis-login-to-internal-api` for the login pod and `felis-build-egress` for
+the build Job; `felis-server-egress` keeps every other game server (lobby included) off
+all private ranges, 8081 among them. A Velocity on another host would put the `velocity`
+token on the wire, which is one more reason the proxy belongs on the node (§1 of
+`docs/operations.md`); a multi-node shape would need TLS on this face first.
+
 - **Internal calls fail to *connect* (not 401)** → the `felis-api-internal` Service
   is missing or its selector no longer matches the api pods. `kubectl -n felis get
   svc felis-api-internal` must show a ClusterIP with 8081; a bare `felis-api` name

plugins/shared/src/main/java/best/lolicon/felis/link/LinkConfigLoader.java

@@ -65,8 +65,10 @@ public final class LinkConfigLoader {
                 + "# Both values are normally injected via environment variables\n"
                 + "# (" + ENV_URL + ", " + ENV_TOKEN + "); this file is the fallback.\n"
                 + "#\n"
-                + "# " + KEY_URL + ": base URL of the felis-api internal face, e.g.\n"
+                + "# " + KEY_URL + ": base URL of the felis-api internal face: the ClusterIP\n"
-                + "#   http://felis-api.felis.svc.cluster.local:8080\n"
+                + "# of Service felis-api-internal, port 8081, e.g. http://10.43.0.10:8081\n"
+                + "# (kubectl -n felis get svc felis-api-internal). The installer writes it for\n"
+                + "# the proxy; it is reachable from the k3s node and permitted pods only.\n"
                 + KEY_URL + "=\n"
                 + "#\n"
                 + "# " + KEY_TOKEN + ": the internal service token (keep this secret).\n"