- Update rate limiter to use exponential backoff instead of fixed limit - Implement progressive delays for failed login attempts (0.5s, 1s, 2s, 4s, 5s max) - Update auth router documentation and endpoint docs - Refactor test suite to match new rate limiting behavior - Update backend development documentation - Clean up unused tasks documentation Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>