fix: use configured cooldown as cap for rate limit wait times

- Cooldown now caps API-provided reset times instead of being a fallback
- Fixed misleading UI descriptions for cooldown settings
- Removed unused cooldownDurationMs from settings object
- Updated default fallback values in frontend to 10s

Co-Authored-By: Claude <noreply@anthropic.com>

src/cli/accounts.js

@@ -142,7 +142,6 @@ function saveAccounts(accounts, settings = {}) {
                 modelRateLimits: acc.modelRateLimits || {}
             })),
             settings: {
-                cooldownDurationMs: 60000,
                 maxRetries: 5,
                 ...settings
             },