Expose peer cache endpoint score reasons

agents/rap-node-agent/internal/mesh/peer_cache.go

@@ -55,6 +55,7 @@ type PeerCacheEntry struct {
 	BestNATType        string                  `json:"best_nat_type,omitempty"`
 	BestPolicyTags     []string                `json:"best_policy_tags,omitempty"`
 	BestCandidateScore int                     `json:"best_candidate_score,omitempty"`
+	BestScoreReasons   []string                `json:"best_score_reasons,omitempty"`
 	EndpointCandidates []PeerEndpointCandidate `json:"endpoint_candidates,omitempty"`
 	RendezvousLeaseID  string                  `json:"rendezvous_lease_id,omitempty"`
 	RelayNodeID        string                  `json:"relay_node_id,omitempty"`
@@ -133,6 +134,7 @@ func NewPeerCache(cfg PeerCacheConfig) *PeerCache {
 			entry.BestNATType = scored[0].Candidate.NATType
 			entry.BestPolicyTags = append([]string{}, scored[0].Candidate.PolicyTags...)
 			entry.BestCandidateScore = scored[0].Score
+			entry.BestScoreReasons = append([]string{}, scored[0].Reasons...)
 			entry.bestScore = scored[0].Score
 			if strings.TrimSpace(scored[0].Candidate.Address) != "" {
 				entry.Endpoint = strings.TrimSpace(scored[0].Candidate.Address)