Remove direct ArgoCD Application/AppProject creation from Backstage templates

## Problem

Backstage scaffolder templates currently create ArgoCD Applications and AppProjects directly in Kubernetes (via the Backstage Kubernetes plugin or kubectl apply). This bypasses the GitOps workflow and creates drift between the desired state in Git and the actual cluster state.

## Expected Behavior

All ArgoCD Application and AppProject resources should be created via GitOps:
1. Backstage templates should generate the YAML manifests and commit them to the appropriate Git repository
2. ArgoCD picks up the new manifests from Git and reconciles them into the cluster
3. No direct Kubernetes API calls from Backstage for ArgoCD resources

## Benefits

- Single source of truth in Git
- Full audit trail via Git history
- Consistent with GitOps principles (the platform's core value proposition)
- Enables PR-based review for new application onboarding
- Eliminates drift between Git state and cluster state

## Scope

- Identify all Backstage templates that create ArgoCD Applications or AppProjects directly
- Refactor them to write YAML files to Git instead
- Ensure ArgoCD ApplicationSets or App-of-Apps pattern picks up the new files
- Update documentation accordingly

Start by inventorying the Backstage scaffolder templates and locating direct ArgoCD resource creation through the Kubernetes plugin or kubectl. Then trace the target Git repository and the ApplicationSets or App-of-Apps pattern that consumes its manifests. Done means all Applications and AppProjects are generated and committed through GitOps, direct calls are removed, and the documentation is updated.

Written by the indexing model from the issue text.