fix: enable all skipped tests and resolve critical logic issues

- Remove all t.Skip() calls (22+ tests) and implement proper mocking
- Fix impossible nil check causing compiler warning in error_logging_test
- Make rate limiter fail-open consistently when Redis unavailable
- Add case sensitivity documentation to policy comparison operators
- Update repository tests with correct SQL query expectations
- Make tests handle DB/Redis unavailability gracefully without panics

middleware/rate_limiter.go

@@ -22,9 +22,10 @@ func DefaultRateLimitConfig() models.RateLimitConfig {
 func RateLimiterMiddleware(config models.RateLimitConfig) func(http.HandlerFunc) http.HandlerFunc {
 	return func(next http.HandlerFunc) http.HandlerFunc {
 		return func(w http.ResponseWriter, r *http.Request) {
-			// Skip rate limiting if Redis is not available
+			// Fail-open: Skip rate limiting if Redis is not available (prevents full outage)
 			if redisclient.RDB == nil {
-				helper.RespondWithError(w, http.StatusServiceUnavailable, "Redis not available")
+				helper.LogError(nil, "Rate limiter: Redis not available, allowing request (fail-open)")
+				next.ServeHTTP(w, r)
 				return
 			}