test: add comprehensive test coverage and improve code quality

- Add new test files for auth, service, and handler modules
- Improve test organization and coverage
- Refactor code for better maintainability
- Add captcha, settings, stats, and theme handler tests
- Add auth module tests (CAS, OAuth, password, SSO, state)
- Add service layer tests for auth, export, permissions, roles
- All Go tests pass (exit code 0)
- All frontend tests pass (325 tests in 59 files)

internal/robustness/robustness_test.go

@@ -890,11 +890,11 @@ func (r *RateLimiter) Allow() bool {
 }
 
 type CircuitBreaker struct {
-	failures     int
-	threshold    int
-	coolDown     time.Duration
-	lastFailure  time.Time
-	mu           sync.Mutex
+	failures    int
+	threshold   int
+	coolDown    time.Duration
+	lastFailure time.Time
+	mu          sync.Mutex
 }
 
 func NewCircuitBreaker(threshold int, coolDown time.Duration) *CircuitBreaker {