feat: rework metrics, add matching/conflict visibility

[gianlucam76]

Metrics (all projectsveltos_ prefixed):

• reconcile_duration_seconds (histogram): cluster_type, cluster_namespace, cluster_name. Duration of programming a Classifier on a workload cluster.
• reconcile_outcome_total (counter): cluster_type, cluster_namespace, cluster_name, status, classifier_name. Terminal Provisioned/Failed outcomes only.
• reconcile_last_success_timestamp_seconds (gauge): same labels minus status. Unix timestamp of the last Provisioned outcome.
• matching_clusters (gauge): classifier_name. Clusters currently matching a Classifier's rules.
• label_conflicts (gauge): classifier_name. Clusters where this Classifier currently has at least one label key it can't manage because another Classifier already owns it.
• mgmt_cluster_matching_clusters / mgmt_cluster_label_conflicts (gauges): classifier_name. Same concepts as above, kept as separate metrics for ManagementClusterClassifier since it's a distinct CRD/reconciler with its own matching semantics (Lua evaluated against management-cluster resources, no deploy-status state machine to hook a duration/outcome metric into).

Also:

• Enable auth-proxy RBAC resources
• Add manifest/service_monitor.yaml

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