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

services/cached_authorization.go

@@ -112,7 +112,7 @@ func NewCachedAuthorizationService() *models.CachedAuthorizationService {
 func AuthorizeWithCache(s *models.CachedAuthorizationService, ctx *models.AuthorizationContext) (*models.AuthorizationResult, error) {
 	startTime := time.Now()
 
-	// Step 1: Get permission from cache()
+	// Step 1: Get permission from cache
 	cacheKey := ctx.Resource + ":" + ctx.Action
 	cacheMutex := s.CacheMutex.(*sync.RWMutex)
 	cacheMutex.RLock()

services/policy_evaluator.go

@@ -40,16 +40,18 @@ func resolveVariables(value string, ctx *models.AuthorizationContext) string {
 	})
 }
 
+// compare evaluates comparison operators between actual and expected values
+// Note: "=" and "!=" are case-sensitive, while IN/CONTAINS/STARTS_WITH/ENDS_WITH are case-insensitive
 func compare(actual, expected, operator string) bool {
 	actual = strings.TrimSpace(actual)
 	expected = strings.TrimSpace(expected)
 
 	switch operator {
 	case "=":
-		return actual == expected
+		return actual == expected // case-sensitive
 
 	case "!=":
-		return actual != expected
+		return actual != expected // case-sensitive
 
 	case ">":
 		return numericCompare(actual, expected, func(a, e float64) bool { return a > e })