fix(homarr): add chart repo to AppProject + simplify values schema

Two fixes:
1. Added https://homarr-labs.github.io/charts to homelab AppProject sourceRepos
   (ArgoCD rejected: "application repo is not permitted in project")

2. Removed env array from homarr-values.yaml
   (Chart template error: "can't evaluate field AUTH_PROVIDERS in type interface {}")

   Chart expects env as key-value object or doesn't support custom env at all.
   Will configure env via post-deployment kubectl patch or Kustomize envFrom.

Allows Homarr Application to sync successfully.

k8s/argocd/projects/homelab-project.yaml

@@ -23,6 +23,7 @@ spec:
     - https://charts.goauthentik.io
     - https://strimzi.io/charts/
     - https://charts.bitnami.com/bitnami
+    - https://homarr-labs.github.io/charts
     - https://go.temporal.io/helm-charts
     - https://portainer.github.io/k8s/
     # Substrate charts (cert-manager, ingress-nginx, reloader) — app-of-apps owned