chore(logging): add debug logs for executor Refresh methods

- Introduced `logrus` for structured debugging across all executors.
- Added debug log messages in `Refresh` methods for better traceability.
- Updated `Manager` to log additional details during refresh checks.

internal/runtime/executor/gemini_executor.go

@@ -14,6 +14,7 @@ import (
 	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
 	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
 	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+	log "github.com/sirupsen/logrus"
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/google"
 )
@@ -165,6 +166,7 @@ func (e *GeminiExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
 }
 
 func (e *GeminiExecutor) Refresh(ctx context.Context, auth *cliproxyauth.Auth) (*cliproxyauth.Auth, error) {
+	log.Debugf("gemini executor: refresh called")
 	// OAuth bearer token refresh for official Gemini API.
 	if auth == nil {
 		return nil, fmt.Errorf("gemini executor: auth is nil")