fix: set PD_MONGO_URI explicitly for in-cluster mongo

When mongo.in_cluster is true, PD_MONGO_URI was not set in the
configmap, causing the Go app to fall back to localhost:27017
which doesn't work inside the cluster. Now uses the FQDN
mongo.<namespace>.svc.cluster.local with the replicaSet parameter.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Junyi Hou

helm-chart/templates/paperdebugger.yaml

@@ -76,6 +76,8 @@ data:
   INFERENCE_BASE_URL: "{{ .Values.inference_base_url }}"
   INFERENCE_API_KEY: "{{ .Values.inference_api_key }}"
   JWT_SIGNING_KEY: "{{ .Values.jwt_signing_key }}"
-  {{ if not .Values.mongo.in_cluster }}
+  {{- if .Values.mongo.in_cluster }}
+  PD_MONGO_URI: "mongodb://mongo.{{ .Values.namespace }}.svc.cluster.local:27017/?replicaSet=in-cluster"
+  {{- else }}
   PD_MONGO_URI: "{{ .Values.mongo.uri }}"
-  {{ end }}
+  {{- end }}