Add helper "waitForCertificates" to KYC Client

[rkeene]

This change adds a waitForCertificates utility method to the KYC client to handle waiting for the certificate from the service provider.

TODO:

1. Finish waiting
2. Handle back-offs
3. Handle permanent fatal errors
4. Deserialize errors
5. Add timeout
6. Add signal to abort
7. Tests

[rkeene]

@copilot Can you finish the TODOs here?

[Copilot]

@rkeene I've opened a new pull request, #92, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

Pull Request Overview

This PR adds a new waitForCertificates method to the KeetaKYCVerification class that polls for certificate availability with configurable timeout and interval parameters.

• Introduces polling mechanism for certificate retrieval
• Adds configurable timeout (default 10 minutes) and poll interval (default 500ms)

[Copilot]

The error handling immediately re-throws all errors, preventing any polling behavior. The method should only re-throw non-recoverable errors and sleep before retrying on expected failures (e.g., certificate not ready yet). The pollInterval parameter should be used to implement the delay between retries.

Suggested change

	for (const startTime = Date.now(); Date.now() - startTime < timeout; ) {
	try {
	return(await this.getCertificates());
	} catch (getCertificatesError) {
	/* XXX:TODO */
	const startTime = Date.now();
	while (Date.now() - startTime < timeout) {
	try {
	return(await this.getCertificates());
	} catch (getCertificatesError: any) {
	// Only retry on expected recoverable errors (e.g., certificate not ready yet)
	// Customize this check as needed for your error types
	if (
	getCertificatesError?.code === 'CERTIFICATE_NOT_READY' ||
	(getCertificatesError?.message && getCertificatesError.message.includes('not ready')) ||
	getCertificatesError?.status === 404 // Example: 404 means not found yet
	) {
	// Wait before retrying
	await new Promise(resolve => setTimeout(resolve, pollInterval));
	continue;
	}
	// Non-recoverable error, re-throw

[Copilot]

The for loop will execute continuously without any delay between iterations, potentially causing high CPU usage and unnecessary API calls. After a failed attempt, the code should wait for 'pollInterval' milliseconds before retrying.

Suggested change

	for (const startTime = Date.now(); Date.now() - startTime < timeout; ) {
	try {
	return(await this.getCertificates());
	} catch (getCertificatesError) {
	/* XXX:TODO */
	throw(getCertificatesError);
	const startTime = Date.now();
	while (Date.now() - startTime < timeout) {
	try {
	return(await this.getCertificates());
	} catch (getCertificatesError) {
	// Wait for pollInterval before retrying
	await new Promise(resolve => setTimeout(resolve, pollInterval));