Add topology spread constraints

Topology spread constraints are necessary for HA environments and should be added to the chart, eg.:

```
topologySpreadConstraints:
- labelSelector:
matchLabels:
cnpg.io/cluster: {{ include "cluster.fullname" . }}
maxSkew: 1
topologyKey: faultdomain
whenUnsatisfiable: ScheduleAnyway
```

Start by locating the chart values and workload template where scheduling options are defined, then compare existing chart conventions. Render the chart with topology spread constraints enabled and verify the generated manifest contains the requested selector, maxSkew, topologyKey, and whenUnsatisfiable settings.

Written by the indexing model from the issue text.