feat(operator): add topologySpreadConstraints support to valkey-operator chart

[somaz94]

Adds an optional topologySpreadConstraints field to the valkey-operator chart's Deployment, resolving #188. It mirrors the existing nodeSelector / affinity / tolerations pattern, and values.yaml already carried a # TODO: topologySpreadConstraints placeholder. Default is [], so the default render is unchanged.

Validation (run locally):

• helm lint ./valkey-operator: 0 failed
• helm unittest ./valkey-operator: 14 passed (3 new cases: default-absent, single, multiple)
• helm template default render is byte-identical to main (only the chart version label changed)

related: #188

[Bloodraven21]

please fix all the merge conflicts in all of your prs

[somaz94]

@Bloodraven21 Thanks! Rebased onto the latest main and resolved the merge conflict. The only conflict was the chart version in valkey-operator/Chart.yaml — bumped it to 0.2.5 (next after the released 0.2.4), moved the CHANGELOG entry under a new ## 0.2.5 section, and updated the README version badge. helm lint passes and helm-unittest is green (25/25). The PR is mergeable again.