feat(P1/P2): 完成TDD开发及P1/P2设计文档

## 设计文档
- multi_role_permission_design: 多角色权限设计 (CONDITIONAL GO)
- audit_log_enhancement_design: 审计日志增强 (CONDITIONAL GO)
- routing_strategy_template_design: 路由策略模板 (CONDITIONAL GO)
- sso_saml_technical_research: SSO/SAML调研 (CONDITIONAL GO)
- compliance_capability_package_design: 合规能力包设计 (CONDITIONAL GO)

## TDD开发成果
- IAM模块: supply-api/internal/iam/ (111个测试)
- 审计日志模块: supply-api/internal/audit/ (40+测试)
- 路由策略模块: gateway/internal/router/ (33+测试)
- 合规能力包: gateway/internal/compliance/ + scripts/ci/compliance/

## 规范文档
- parallel_agent_output_quality_standards: 并行Agent产出质量规范
- project_experience_summary: 项目经验总结 (v2)
- 2026-04-02-p1-p2-tdd-execution-plan: TDD执行计划

## 评审报告
- 5个CONDITIONAL GO设计文档评审报告
- fix_verification_report: 修复验证报告
- full_verification_report: 全面质量验证报告
- tdd_module_quality_verification: TDD模块质量验证
- tdd_execution_summary: TDD执行总结

依据: Superpowers执行框架 + TDD规范

gateway/internal/router/engine/routing_engine.go

@@ -0,0 +1,63 @@
+package engine
+
+import (
+	"context"
+	"errors"
+
+	"lijiaoqiao/gateway/internal/router/strategy"
+)
+
+// ErrStrategyNotFound 策略未找到
+var ErrStrategyNotFound = errors.New("strategy not found")
+
+// RoutingMetrics 路由指标接口
+type RoutingMetrics interface {
+	// RecordSelection 记录路由选择
+	RecordSelection(provider string, strategyName string, decision *strategy.RoutingDecision)
+}
+
+// RoutingEngine 路由引擎
+type RoutingEngine struct {
+	strategies map[string]strategy.StrategyTemplate
+	metrics    RoutingMetrics
+}
+
+// NewRoutingEngine 创建路由引擎
+func NewRoutingEngine() *RoutingEngine {
+	return &RoutingEngine{
+		strategies: make(map[string]strategy.StrategyTemplate),
+		metrics:    nil,
+	}
+}
+
+// RegisterStrategy 注册路由策略
+func (e *RoutingEngine) RegisterStrategy(name string, template strategy.StrategyTemplate) {
+	e.strategies[name] = template
+}
+
+// SetMetrics 设置指标收集器
+func (e *RoutingEngine) SetMetrics(metrics RoutingMetrics) {
+	e.metrics = metrics
+}
+
+// SelectProvider 根据策略选择Provider
+func (e *RoutingEngine) SelectProvider(ctx context.Context, req *strategy.RoutingRequest, strategyName string) (*strategy.RoutingDecision, error) {
+	// 查找策略
+	tpl, ok := e.strategies[strategyName]
+	if !ok {
+		return nil, ErrStrategyNotFound
+	}
+
+	// 执行策略选择
+	decision, err := tpl.SelectProvider(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+
+	// 记录指标
+	if e.metrics != nil && decision != nil {
+		e.metrics.RecordSelection(decision.Provider, decision.Strategy, decision)
+	}
+
+	return decision, nil
+}

gateway/internal/router/engine/routing_engine_test.go

@@ -0,0 +1,154 @@
+package engine
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"lijiaoqiao/gateway/internal/adapter"
+	"lijiaoqiao/gateway/internal/router/strategy"
+)
+
+// TestRoutingEngine_SelectProvider 测试路由引擎根据策略选择provider
+func TestRoutingEngine_SelectProvider(t *testing.T) {
+	engine := NewRoutingEngine()
+
+	// 注册策略
+	costBased := strategy.NewCostBasedTemplate("CostBased", strategy.CostParams{
+		MaxCostPer1KTokens: 1.0,
+	})
+
+	// 注册providers
+	costBased.RegisterProvider("ProviderA", &MockProvider{
+		name:            "ProviderA",
+		costPer1KTokens: 0.5,
+		available:       true,
+		models:          []string{"gpt-4"},
+	})
+	costBased.RegisterProvider("ProviderB", &MockProvider{
+		name:            "ProviderB",
+		costPer1KTokens: 0.3, // 最低成本
+		available:       true,
+		models:          []string{"gpt-4"},
+	})
+
+	engine.RegisterStrategy("cost_based", costBased)
+
+	req := &strategy.RoutingRequest{
+		Model:   "gpt-4",
+		UserID:  "user123",
+		MaxCost: 1.0,
+	}
+
+	decision, err := engine.SelectProvider(context.Background(), req, "cost_based")
+
+	assert.NoError(t, err)
+	assert.NotNil(t, decision)
+	assert.Equal(t, "ProviderB", decision.Provider, "Should select lowest cost provider")
+	assert.True(t, decision.TakeoverMark, "TakeoverMark should be true for M-008")
+}
+
+// TestRoutingEngine_DecisionMetrics 测试路由决策记录metrics
+func TestRoutingEngine_DecisionMetrics(t *testing.T) {
+	engine := NewRoutingEngine()
+
+	// 创建mock metrics collector
+	engine.metrics = &MockRoutingMetrics{}
+
+	// 注册策略
+	costBased := strategy.NewCostBasedTemplate("CostBased", strategy.CostParams{
+		MaxCostPer1KTokens: 1.0,
+	})
+
+	costBased.RegisterProvider("ProviderA", &MockProvider{
+		name:            "ProviderA",
+		costPer1KTokens: 0.5,
+		available:       true,
+		models:          []string{"gpt-4"},
+	})
+
+	engine.RegisterStrategy("cost_based", costBased)
+
+	req := &strategy.RoutingRequest{
+		Model:  "gpt-4",
+		UserID: "user123",
+	}
+
+	decision, err := engine.SelectProvider(context.Background(), req, "cost_based")
+
+	assert.NoError(t, err)
+	assert.NotNil(t, decision)
+
+	// 验证metrics被记录
+	metrics := engine.metrics.(*MockRoutingMetrics)
+	assert.True(t, metrics.recordCalled, "RecordSelection should be called")
+	assert.Equal(t, "ProviderA", metrics.lastProvider, "Provider should be recorded")
+}
+
+// MockProvider 用于测试的Mock Provider
+type MockProvider struct {
+	name            string
+	costPer1KTokens float64
+	qualityScore    float64
+	latencyMs       int64
+	available       bool
+	models          []string
+}
+
+func (m *MockProvider) ChatCompletion(ctx context.Context, model string, messages []adapter.Message, options adapter.CompletionOptions) (*adapter.CompletionResponse, error) {
+	return nil, nil
+}
+
+func (m *MockProvider) ChatCompletionStream(ctx context.Context, model string, messages []adapter.Message, options adapter.CompletionOptions) (<-chan *adapter.StreamChunk, error) {
+	return nil, nil
+}
+
+func (m *MockProvider) GetUsage(response *adapter.CompletionResponse) adapter.Usage {
+	return adapter.Usage{}
+}
+
+func (m *MockProvider) MapError(err error) adapter.ProviderError {
+	return adapter.ProviderError{}
+}
+
+func (m *MockProvider) HealthCheck(ctx context.Context) bool {
+	return m.available
+}
+
+func (m *MockProvider) ProviderName() string {
+	return m.name
+}
+
+func (m *MockProvider) SupportedModels() []string {
+	return m.models
+}
+
+func (m *MockProvider) GetCostPer1KTokens() float64 {
+	return m.costPer1KTokens
+}
+
+func (m *MockProvider) GetQualityScore() float64 {
+	return m.qualityScore
+}
+
+func (m *MockProvider) GetLatencyMs() int64 {
+	return m.latencyMs
+}
+
+// MockRoutingMetrics 用于测试的Mock Metrics
+type MockRoutingMetrics struct {
+	recordCalled  bool
+	lastProvider  string
+	lastStrategy  string
+	takeoverMark  bool
+}
+
+func (m *MockRoutingMetrics) RecordSelection(provider string, strategyName string, decision *strategy.RoutingDecision) {
+	m.recordCalled = true
+	m.lastProvider = provider
+	m.lastStrategy = strategyName
+	if decision != nil {
+		m.takeoverMark = decision.TakeoverMark
+	}
+}