fix(auth): Make round-robin auth selection deterministic

sdk/cliproxy/auth/manager.go

@@ -15,6 +15,7 @@ import (
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
 	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
 	log "github.com/sirupsen/logrus"
+	"sort"
 )
 
 // ProviderExecutor defines the contract required by Manager to execute provider calls.
@@ -796,6 +797,12 @@ func (m *Manager) pickNext(ctx context.Context, provider, model string, opts cli
 		}
 		candidates = append(candidates, auth.Clone())
 	}
+	// Ensure stable iteration order across requests to make round-robin deterministic.
+	// Go map iteration order is randomized; without sorting, the selector's index-based
+	// rotation may appear non-round-robin.
+	if len(candidates) > 1 {
+		sort.Slice(candidates, func(i, j int) bool { return candidates[i].ID < candidates[j].ID })
+	}
 	m.mu.RUnlock()
 	if len(candidates) == 0 {
 		return nil, nil, &Error{Code: "auth_not_found", Message: "no auth available"}