Retry with backoff for any agent tool call
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const { withRetry } = require("./retry");
const result = await withRetry(() => callSomethingFlaky(), { maxAttempts: 4 });

Wraps any async function. Retries on failure with exponential backoff (200ms, 400ms, 800ms...),
then throws a clear error naming the attempt count if every attempt fails. See demo.js for a
runnable example of both outcomes.
