refactor(access): migrate config-api-key provider to internal package

- Moved `config-api-key` provider logic from SDK to the internal `config_access` package.
- Updated provider registration and initialization to ensure proper management via `Register` function.
- Removed redundant `config-api-key` documentation, simplifying configuration examples.
- Adjusted related imports and reconciliations for seamless integration with the new structure.

internal/access/reconcile.go

@@ -6,6 +6,7 @@ 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"
@@ -21,6 +22,8 @@ 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 {