fix(gateway): 修复RuleEngine中regexp编译错误和并发安全问题

P0-05: regexp.Compile错误被静默忽略
- extractMatch函数现在返回(string, error)
- 正确处理regexp.Compile错误，返回格式化错误信息
- 修复无效正则导致的panic问题

P0-06: compiledPatterns非线程安全
- 添加sync.RWMutex保护map并发访问
- matchRegex和extractMatch使用读锁/写锁保护
- 实现双重检查锁定模式优化性能

测试验证:
- 使用-race flag验证无数据竞争
- 并发100个goroutine测试通过

gateway/internal/compliance/rules/engine_test.go

@@ -0,0 +1,111 @@
+package rules
+
+import (
+	"sync"
+	"testing"
+)
+
+// ==================== P0-05 测试: regexp编译错误被静默忽略 ====================
+
+// TestExtractMatch_InvalidRegex_P0_05 测试无效正则表达式被静默忽略的问题
+// 问题: extractMatch在regexp.Compile失败时会panic，因为错误被丢弃
+func TestExtractMatch_InvalidRegex_P0_05(t *testing.T) {
+	loader := NewRuleLoader()
+	engine := NewRuleEngine(loader)
+
+	// 使用无效的正则表达式 - 这会导致panic因为错误被忽略
+	invalidPattern := "[invalid" // 无效的正则表达式，缺少闭合括号
+
+	// 捕获panic来验证问题存在
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("P0-05 问题确认: extractMatch对无效正则发生了panic: %v", r)
+			t.Log("问题: regexp.Compile错误被丢弃，导致后续操作panic")
+		}
+	}()
+
+	// 如果没有panic，说明问题已修复
+	result, err := engine.extractMatch(invalidPattern, "test content")
+	if err != nil {
+		t.Logf("P0-05 问题已修复: extractMatch正确返回错误: %v, result=%q", err, result)
+	} else {
+		t.Errorf("P0-05 未修复: extractMatch应返回错误但没有返回")
+	}
+}
+
+// ==================== P0-06 测试: compiledPatterns非线程安全 ====================
+
+// TestRuleEngine_ConcurrentAccess_P0_06 测试并发访问时的数据竞争
+// 使用race detector检测数据竞争
+func TestRuleEngine_ConcurrentAccess_P0_06(t *testing.T) {
+	loader := NewRuleLoader()
+	engine := NewRuleEngine(loader)
+
+	pattern := "test"
+	content := "this is a test content"
+
+	var wg sync.WaitGroup
+	numGoroutines := 100
+
+	// 并发调用matchRegex
+	for i := 0; i < numGoroutines; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			_ = engine.matchRegex(pattern, content)
+		}()
+	}
+
+	// 同时并发调用extractMatch
+	for i := 0; i < numGoroutines; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			_, _ = engine.extractMatch(pattern, content)
+		}()
+	}
+
+	// 同时并发调用Match
+	rule := Rule{
+		ID: "test-rule",
+		Matchers: []Matcher{
+			{Type: "regex_match", Pattern: pattern},
+		},
+	}
+
+	for i := 0; i < numGoroutines; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			_ = engine.Match(rule, content)
+		}()
+	}
+
+	wg.Wait()
+	t.Log("P0-06 验证: 并发测试完成")
+}
+
+// TestRuleEngine_ConcurrentMapAccess_P0_06 测试map并发读写问题
+func TestRuleEngine_ConcurrentMapAccess_P0_06(t *testing.T) {
+	loader := NewRuleLoader()
+	engine := NewRuleEngine(loader)
+
+	patterns := []string{"test1", "test2", "test3", "test4", "test5"}
+	content := "test1 test2 test3 test4 test5"
+
+	var wg sync.WaitGroup
+	for _, pattern := range patterns {
+		p := pattern
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for i := 0; i < 50; i++ {
+				_ = engine.matchRegex(p, content)
+				_, _ = engine.extractMatch(p, content)
+			}
+		}()
+	}
+
+	wg.Wait()
+	t.Log("P0-06 验证: 并发读写测试完成")
+}