Update Go module path from Gitea to GitHub

Change module path from:
  gitea.engen.priv.no/klauvsteinen/unifi-network-operator
To:
  github.com/vegardengen/unifi-network-operator

This fixes the module path mismatch error in GitHub Actions.

Changes:
- Updated go.mod module declaration
- Updated all import statements in Go files
- Updated kustomization and ko config files
- Ran go mod tidy to update dependencies

This is required for the project to build correctly on GitHub.

config/manager/kustomization.yaml

@@ -4,5 +4,5 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 images:
 - name: controller
-  newName: gitea.engen.priv.no/klauvsteinen/unifi-network-operator-controller
+  newName: github.com/vegardengen/unifi-network-operator-controller
   newTag: latest