- Add IAM Identity Center (IDC) authentication with CLI flags (--kiro-idc-login, --kiro-idc-start-url, --kiro-idc-region) and login flow
- Add ProfileArn auto-fetching in Execute/ExecuteStream for imported IDC accounts
- Simplify endpoint preference with map-based alias lookup and getAuthValue helper
- Redesign fingerprint as global singleton with external config and per-account deterministic generation
- Add StartURL and FingerprintConfig fields to Kiro config
- Add AgentContinuationID/AgentTaskType support in Kiro translators
- Add comprehensive tests for executor, fingerprint, SSO OIDC, and AWS helpers
- Add CLI login documentation to README
The background refresher was skipping token files with auth_method values
like 'IdC' or 'IDC' because the comparison was case-sensitive and only
matched lowercase 'idc'.
This fix normalizes the auth_method to lowercase before comparison in:
- token_repository.go: readTokenFile() when filtering tokens to refresh
- background_refresh.go: refreshSingle() when selecting refresh method
Fixes the issue where 'IdC' != 'idc' caused tokens to be skipped entirely.