Add --jira.apiToken alias for Jira Cloud authentication

## Summary

The current CLI authentication options are confusing for Jira Cloud users. The `--jira.password` option is used with API tokens, but the naming suggests a password.

## Current State

For Jira Cloud API token authentication, users must use:
```bash
--jira.username your-email@example.com \
--jira.password YOUR_API_TOKEN
```

This is counterintuitive since the "password" is actually an API token.

## Proposed Change

Add a `--jira.apiToken` alias (or alternative option) that makes Jira Cloud authentication clearer:

```bash
--jira.username your-email@example.com \
--jira.apiToken YOUR_API_TOKEN
```

## Implementation Notes

- Could be a simple alias to `--jira.password` in the yargs configuration
- Or a new dedicated auth method `jiraClientWithApiToken(email, apiToken)` for clarity
- Should update help text to explain the difference between Server PAT and Cloud API tokens

## Auth Methods Reference

| Jira Type | Current Option | Auth Style |
|-----------|----------------|------------|
| Server/DC PAT | `--jira.personalAccessToken` | Bearer token |
| Cloud API Token | `--jira.username` + `--jira.password` | Basic auth |
| OAuth | Consumer key/secret + access tokens | OAuth 1.0a |