Auth profiles in cooldown (due to rate limiting) were being attempted,
causing unnecessary retries and delays. This fix ensures:
1. Initial profile selection skips profiles in cooldown
2. Profile rotation (after failures) skips cooldown profiles
3. Clear error message when all profiles are unavailable
Tests added:
- Skips profiles in cooldown during initial selection
- Skips profiles in cooldown when rotating after failure
Fixes#1316
