Fix garage secret file permissions

The secret volume's default file mode (0644) is world-readable, and
Garage refuses to start with rpc_secret_file/admin_token_file/
metrics_token_file at anything looser than 0600. Set defaultMode:
0600 on the secrets volume.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ZA4cJygj4VPCYVms4TDrH

garage/Chart.yaml

@@ -4,5 +4,5 @@ description: A Helm chart for Garage, a lightweight S3-compatible object store
 type: application
 annotations:
   version-source: dockerhub-tags-pattern:dxflrs/garage:^v[0-9]+\.[0-9]+\.[0-9]+$
-version: 0.1.1
+version: 0.1.2
 appVersion: "v2.4.1"

garage/templates/deployment.yaml

@@ -72,6 +72,7 @@ spec:
         - name: secrets
           secret:
             secretName: {{ .Values.existingSecret }}
+            defaultMode: 0600
             items:
               - key: {{ .Values.secretKeys.rpcSecret }}
                 path: rpc-secret