Multiple RateLimitMiddleware instances were each calling
check_allowed() on every request, halving the effective global
limit (200 req/min became ~100). Added path_prefixes and skip_paths
so each instance only checks the paths it owns.
- Auth middleware scoped to /api/v1/auth/login and /api/v1/setup
- History middleware scoped to /api/v1/history
- Global middleware skips auth and history paths
- Updated tests to match single-count behavior