refactor(all): replace manual pointer assignments with new to enhance code readability and maintainability

sdk/auth/antigravity.go

@@ -28,8 +28,7 @@ func (AntigravityAuthenticator) Provider() string { return "antigravity" }
 
 // RefreshLead instructs the manager to refresh five minutes before expiry.
 func (AntigravityAuthenticator) RefreshLead() *time.Duration {
-	lead := 5 * time.Minute
-	return &lead
+	return new(5 * time.Minute)
 }
 
 // Login launches a local OAuth flow to obtain antigravity tokens and persists them.

sdk/auth/claude.go

@@ -32,8 +32,7 @@ func (a *ClaudeAuthenticator) Provider() string {
 }
 
 func (a *ClaudeAuthenticator) RefreshLead() *time.Duration {
-	d := 4 * time.Hour
-	return &d
+	return new(4 * time.Hour)
 }
 
 func (a *ClaudeAuthenticator) Login(ctx context.Context, cfg *config.Config, opts *LoginOptions) (*coreauth.Auth, error) {

sdk/auth/codex.go

@@ -34,8 +34,7 @@ func (a *CodexAuthenticator) Provider() string {
 }
 
 func (a *CodexAuthenticator) RefreshLead() *time.Duration {
-	d := 5 * 24 * time.Hour
-	return &d
+	return new(5 * 24 * time.Hour)
 }
 
 func (a *CodexAuthenticator) Login(ctx context.Context, cfg *config.Config, opts *LoginOptions) (*coreauth.Auth, error) {

sdk/auth/iflow.go

@@ -26,8 +26,7 @@ func (a *IFlowAuthenticator) Provider() string { return "iflow" }
 
 // RefreshLead indicates how soon before expiry a refresh should be attempted.
 func (a *IFlowAuthenticator) RefreshLead() *time.Duration {
-	d := 24 * time.Hour
-	return &d
+	return new(24 * time.Hour)
 }
 
 // Login performs the OAuth code flow using a local callback server.

sdk/auth/qwen.go

@@ -27,8 +27,7 @@ func (a *QwenAuthenticator) Provider() string {
 }
 
 func (a *QwenAuthenticator) RefreshLead() *time.Duration {
-	d := 3 * time.Hour
-	return &d
+	return new(3 * time.Hour)
 }
 
 func (a *QwenAuthenticator) Login(ctx context.Context, cfg *config.Config, opts *LoginOptions) (*coreauth.Auth, error) {