chore(infra): bump prop to 4 replicas for talos5 (NUC)

talos5 is a NUC7i5 with 32GB RAM and a Samsung 980 Pro NVMe. Adding
a 4th hot-path replica lets the anti-affinity rule place one pod
per physical host across node1/2/3/5 and gives the hourly f00-f18
grid chain 4-way parallel fan-out, with the NVMe-backed pod
handling its share of grib extraction.

k8s/deployment.yaml

@@ -4,7 +4,7 @@ metadata:
   name: prop
   namespace: prop
 spec:
-  replicas: 3
+  replicas: 4
   minReadySeconds: 5
   strategy:
     type: RollingUpdate