Exclude namespaces

[piceri]

This PR introduces a -exclude-namespaces flag that accepts a comma separated list of namespaces to exclude from monitoring.

I checked to see if the -namespace flag could also accept a comma separated list but it seems FieldSelector ANDs together multiple values and you cannot OR them together.

[Copilot]

Pull request overview

Adds support for excluding specific Kubernetes namespaces from deployment-tracker monitoring via a new CLI flag.

Changes:

• Extends CLI with -exclude-namespaces and prevents using it together with -namespace.
• Refactors controller informer setup into createInformerFactory(...) and adds field-selector-based namespace exclusion.
• Documents the new flag and the mutual exclusivity rule in the README.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
internal/controller/controller.go	Refactors informer factory creation and adds field-selector logic to exclude namespaces.
cmd/deployment-tracker/main.go	Introduces -exclude-namespaces flag, validation, and passes it into the controller.
README.md	Documents the new CLI flag and notes that it can’t be combined with -namespace.

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[malancas]

The copilot comments make sense to me. Looks good overall