fix - Add Labels on Kubernetes Objects

[pranavcracker]

Description

Adds app.kubernetes.io/* standard labels to Deployment resources and introduces the find_image helper to support image override via deployDescriptor.

Chnages

• Added find_image Helm helper to _helpers.tpl — checks deployDescriptor for image override, falls back to the default image value
• Added app.kubernetes.io/* labels (name, instance, version, component, part-of, managed-by, technology) to metadata.labels and spec.template.metadata.labels on both site-manager and paas-geo-monitor Deployments
• Labels are guarded by {{- if .Values.SERVICE_NAME }} so deployments without these values set are unaffected
• Switched image reference in both Deployment templates to use find_image instead of a direct value reference

Dependency: This branch is based on #219 (security hardening). Merge #219 first, then merge this PR.