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>

internal/auth/interface.go

@@ -0,0 +1,11 @@
+package auth
+
+import "context"
+
+// SessionRefresher defines the interface for refreshing authentication tokens.
+// This allows the API client to automatically refresh tokens on 401 responses.
+type SessionRefresher interface {
+	RefreshToken() error
+	RefreshTokenWithContext(ctx context.Context) error
+	GetSession() (*Session, error)
+}