feat: implement automatic auth token refresh on 401 with context support (FRE-4763)

- Add SessionRefresher interface for token refresh abstraction
- Update ProtonMailClient to auto-refresh on 401 responses
- Add DoWithContext method for context-aware HTTP requests
- Update SessionManager with RefreshTokenWithContext method
- Update LoginWithCredentials and LoginInteractive to accept context
- Add checkAuthenticatedWithManager helper for commands needing session manager
- All API methods now support proper cancellation via context.Context

Files changed:
- internal/api/client.go - Auto-refresh on 401, context support
- internal/auth/session.go - Context-aware refresh and login methods
- internal/auth/interface.go - SessionRefresher interface
- cmd/mail.go, cmd/draft.go, cmd/folders.go - Updated to use new helpers
- cmd/auth.go - Context support for login commands

Co-Authored-By: Paperclip <noreply@paperclip.ing>

cmd/folders.go

@@ -370,7 +370,7 @@ func newLabelClient() (*labels.Client, error) {
 		return nil, fmt.Errorf("not authenticated: %w", err)
 	}
 
-	apiClient := api.NewProtonMailClient(cfg)
+	apiClient := api.NewProtonMailClient(cfg, sessionMgr)
 	apiClient.SetAuthHeader(session.AccessToken)
 
 	return labels.NewClient(apiClient), nil