fix legion-apps argo umbrella to use gitea DNS name

The legion-apps Application root was hardcoded to the OLD legion's gitea
cluster IP (10.43.1.53:3000). On the new GCP legion, the gitea service
got a different cluster IP (10.43.15.98), so the umbrella has been
ComparisonError-stuck since the cluster move on 2026-04-28. That meant
new Application manifests in apps/ never got materialized in argocd —
neuron-web was the first new app to need it after the move.

All other apps reference http://gitea.git.svc.cluster.local:3000/...
(the stable DNS name). Bringing the three legion-apps spots in argocd.tf
in line with that convention so the next gitea cluster-IP shuffle
doesn't re-break the umbrella.

servers/legion/argocd.tf

@@ -36,7 +36,7 @@ resource "helm_release" "argocd" {
         server.insecure: true  # TLS terminated at Traefik
       repositories:
         gitea-infrastructure:
-          url: http://10.43.1.53:3000/will/infrastructure.git
+          url: http://gitea.git.svc.cluster.local:3000/will/infrastructure.git
           name: infrastructure
           type: git
   YAML
@@ -96,7 +96,7 @@ resource "kubernetes_secret" "argocd_gitea_repo" {
 
   data = {
     type     = "git"
-    url      = "http://10.43.1.53:3000/will/infrastructure.git"
+    url      = "http://gitea.git.svc.cluster.local:3000/will/infrastructure.git"
     username = "will"
     password = var.gitea_api_token
   }
@@ -136,7 +136,7 @@ resource "kubernetes_manifest" "argocd_root_app" {
     spec = {
       project = "default"
       source = {
-        repoURL        = "http://10.43.1.53:3000/will/infrastructure.git"
+        repoURL        = "http://gitea.git.svc.cluster.local:3000/will/infrastructure.git"
         targetRevision = "main"
         path           = "servers/legion/apps"
       }