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/auth.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"context"
 	"fmt"
 	"os"
 
@@ -26,7 +27,7 @@ func loginCmd() *cobra.Command {
 				return fmt.Errorf("failed to create session manager: %w", err)
 			}
 
-			return manager.LoginInteractive(cfg.APIBaseURL)
+			return manager.LoginInteractive(context.Background(), cfg.APIBaseURL)
 		},
 	}