rename: homelab-gateway → telegram-gateway

Aligns the project name with the public URL (tg.arcodange.fr) and the
Arcodange organization conventions. The 'homelab-gateway' name was too
generic.

Touches: chart name + helpers, image registry path, Go module path,
secret/configmap names, deployment mountPath, all docs.

chart/templates/vaultauth.yaml

@@ -5,13 +5,13 @@ metadata:
   name: auth
   namespace: {{ .Release.Namespace }}
   labels:
-    {{- include "homelab-gateway.labels" . | nindent 4 }}
+    {{- include "telegram-gateway.labels" . | nindent 4 }}
 spec:
   method: kubernetes
   mount: kubernetes
   kubernetes:
     role: {{ .Values.vault.role }}
-    serviceAccount: {{ include "homelab-gateway.serviceAccountName" . }}
+    serviceAccount: {{ include "telegram-gateway.serviceAccountName" . }}
     audiences:
       - vault
 {{- end }}