Pre-create neuron-marketplace.db in initContainer for subPath mount

subPath mounts require the source file to exist on the PVC before the
main container starts. Add 'touch /data/neuron-marketplace.db' to the
initContainer so the subPath mount can bind the file at /app/neuron-marketplace.db.

servers/legion/k8s/neuron-technologies/prod/mcp-deployment.yaml

@@ -22,7 +22,7 @@ spec:
         slot: blue
         env: prod
       annotations:
-        config-hash: "marketplace-db-subpath-v2"
+        config-hash: "marketplace-db-subpath-v3"
     spec:
       terminationGracePeriodSeconds: 30
       securityContext:
@@ -33,7 +33,7 @@ spec:
       initContainers:
         - name: fix-data-ownership
           image: busybox:1.36
-          command: ["sh", "-c", "chown -R 1000:1000 /data"]
+          command: ["sh", "-c", "touch /data/neuron-marketplace.db && chown -R 1000:1000 /data"]
           securityContext:
             runAsUser: 0
             runAsNonRoot: false