feat: add automatic version labeling to pods based on container images

[allthatjazzleo]

Summary

Adds automatic version labeling to pods by extracting version information from container images and setting it as a Kubernetes label using kube.VersionLabel.

Problem

Previously, pods created by the cosmos-operator lacked version information in their labels, making it difficult for operators and monitoring tools to identify which version of the blockchain software was running in each pod.

Solution

• Added updatePodVersionLabel() function that extracts version from container image using kube.ParseImageVersion()
• Integrated version labeling at two key points:
  1. When setting versioned images from chain versions
  2. When overriding images via pod overrides
• Comprehensive test coverage to ensure version labels are correctly set

Changes Made

• New function: updatePodVersionLabel() in internal/fullnode/build_pods.go
• Integration points: Called in pod_builder.go when images are set or overridden
• Enhanced tests: Added assertions in both build_pods_test.go and pod_builder_test.go