refactor(access): centralize configaccess.Register and remove redundant calls

- Added centralized `configaccess.Register` invocation in `server` initialization.
- Removed duplicate `Register` calls from `reconcile.go` and `builder.go`.
- Simplified logic by removing unnecessary `nil` checks in provider entry collection.

cmd/server/main.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"path/filepath"
 
+	configaccess "github.com/router-for-me/CLIProxyAPI/v6/internal/access/config_access"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/cmd"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/logging"
@@ -66,7 +67,7 @@ func main() {
 				return
 			}
 			s := fmt.Sprintf("  -%s", f.Name)
-			name, usage := flag.UnquoteUsage(f)
+			name, unquoteUsage := flag.UnquoteUsage(f)
 			if name != "" {
 				s += " " + name
 			}
@@ -75,8 +76,8 @@ func main() {
 			} else {
 				s += "\n    "
 			}
-			if usage != "" {
-				s += usage
+			if unquoteUsage != "" {
+				s += unquoteUsage
 			}
 			if f.DefValue != "" && f.DefValue != "false" && f.DefValue != "0" {
 				s += fmt.Sprintf(" (default %s)", f.DefValue)
@@ -136,6 +137,9 @@ func main() {
 	// Register the shared token store once so all components use the same persistence backend.
 	sdkAuth.RegisterTokenStore(sdkAuth.NewFileTokenStore())
 
+	// Register built-in access providers before constructing services.
+	configaccess.Register()
+
 	// Handle different command modes based on the provided flags.
 
 	if login {

internal/access/reconcile.go

@@ -6,7 +6,6 @@ import (
 	"sort"
 	"strings"
 
-	configaccess "github.com/router-for-me/CLIProxyAPI/v6/internal/access/config_access"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
 	sdkaccess "github.com/router-for-me/CLIProxyAPI/v6/sdk/access"
 	sdkConfig "github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
@@ -22,8 +21,6 @@ func ReconcileProviders(oldCfg, newCfg *config.Config, existing []sdkaccess.Prov
 		return nil, nil, nil, nil, nil
 	}
 
-	configaccess.Register()
-
 	existingMap := make(map[string]sdkaccess.Provider, len(existing))
 	for _, provider := range existing {
 		if provider == nil {
@@ -206,9 +203,6 @@ func accessProviderMap(cfg *config.Config) map[string]*sdkConfig.AccessProvider
 
 func collectProviderEntries(cfg *config.Config) []*sdkConfig.AccessProvider {
 	entries := make([]*sdkConfig.AccessProvider, 0, len(cfg.Access.Providers))
-	if cfg == nil {
-		return entries
-	}
 	for i := range cfg.Access.Providers {
 		providerCfg := &cfg.Access.Providers[i]
 		if providerCfg.Type == "" {

sdk/cliproxy/builder.go

@@ -6,7 +6,6 @@ package cliproxy
 import (
 	"fmt"
 
-	configaccess "github.com/router-for-me/CLIProxyAPI/v6/internal/access/config_access"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/api"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
 	sdkaccess "github.com/router-for-me/CLIProxyAPI/v6/sdk/access"
@@ -185,7 +184,6 @@ func (b *Builder) Build() (*Service, error) {
 	if accessManager == nil {
 		accessManager = sdkaccess.NewManager()
 	}
-	configaccess.Register()
 
 	providers, err := sdkaccess.BuildProviders(&b.cfg.SDKConfig)
 	if err != nil {