fix(dashboard): add tmp volumeMount for readOnlyRootFilesystem

Next.js standalone mode needs a writable /tmp directory for cache, temp files, and logs.

With , the container was crashing after "Ready in 228ms" (EOF in log stream).

Added the standard emptyDir volumeMount used by other services.

This should make the dashboard stable and accessible on tailnet.

apps/base/customer1/trading-platform/dashboard/deployment.yaml

@@ -58,6 +58,9 @@ spec:
                 secretKeyRef:
                   name: trading-db-credentials
                   key: password
+          volumeMounts:
+            - name: tmp
+              mountPath: /tmp
           startupProbe:
             httpGet:
               path: /
@@ -77,3 +80,6 @@ spec:
               port: 3000
             initialDelaySeconds: 5
             periodSeconds: 10
+      volumes:
+        - name: tmp
+          emptyDir: {}