feat: add maxDelayMs setting to cap server-requested retry delays

When a provider (e.g., Google Gemini CLI) requests a retry delay longer
than maxDelayMs (default: 60s), the request fails immediately with an
informative error instead of waiting silently for hours.

The error is then handled by agent-level auto-retry, which shows the
delay to the user and allows aborting with Escape.

- Add maxRetryDelayMs to StreamOptions (packages/ai)
- Add maxRetryDelayMs to AgentOptions (packages/agent)
- Add retry.maxDelayMs to settings (packages/coding-agent)
- Update _isRetryableError to match 'retry delay' errors

fixes #1123

packages/ai/src/providers/simple-options.ts

@@ -9,6 +9,7 @@ export function buildBaseOptions(model: Model<Api>, options?: SimpleStreamOption
 		sessionId: options?.sessionId,
 		headers: options?.headers,
 		onPayload: options?.onPayload,
+		maxRetryDelayMs: options?.maxRetryDelayMs,
 	};
 }