Add ArgoCD integration for Status Dashboard

[LukasCuperDT]

Summary

Adds ArgoCD project, repository, and application configuration for deploying status-dashboard-api from the stackmon/stackmon-deploy repository.

Changes

ArgoCD Project

• New status-dashboard AppProject restricted to preprod cluster only
• Full access to all namespaces, source repos, and cluster resources within preprod

ArgoCD Repository

• Extended argocd-repositories.yaml template to support a repositorySecrets list with optional username/password fields (backward-compatible with existing single repositorySecret)
• Added stackmon-deploy private repository (https://github.com/stackmon/stackmon-deploy.git) with auth placeholders

ArgoCD Application

• status-dashboard-api application in status-dashboard namespace
• Sources from stackmon/stackmon-deploy repo (branch: main, path: charts/status-dashboard-api)
• Uses argocd-vault-plugin-helm-with-args plugin with dev values overlay
• Auto-sync with prune, self-heal, and CreateNamespace enabled

Dependencies

• stackmon/stackmon-deploy PR required to merge the vault-agent → AVP migration first
• Repository credentials (username/password) need to be set with actual base64-encoded values before deployment

[gitguardian]

️✅ There are no secrets present in this pull request anymore.

If these secrets were true positive and are still valid, we highly recommend you to revoke them.
While these secrets were previously flagged, we no longer have a reference to the
specific commits where they were detected. Once a secret has been leaked into a git
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Find here more information about risks.

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