feat: 初始化 git-air AI 代码评审 CLI 工具

新增多模型 LLM 客户端、Git diff 提取与过滤、配置管理及 pre-commit 钩子支持。

internal/reviewer/reviewer.go

@@ -0,0 +1,40 @@
+package reviewer
+
+import (
+	"context"
+	"fmt"
+	"git-air/internal/llm"
+	"strings"
+)
+
+type Reviewer struct {
+	client       *llm.Client
+	repoRoot     string
+	customPrompt string
+}
+
+// NewReviewer 初始化评审引擎
+// customPrompt 可传入用户自定义配置的 Prompt，传空字符串则使用默认 Prompt
+func NewReviewer(client *llm.Client, repoRoot string, customPrompt string) *Reviewer {
+	return &Reviewer{
+		client:       client,
+		repoRoot:     repoRoot,
+		customPrompt: customPrompt,
+	}
+}
+
+// Execute 执行代码评审
+func (r *Reviewer) Execute(ctx context.Context, diff string, stream bool, onChunk func(chunk string)) (string, error) {
+	if strings.TrimSpace(diff) == "" {
+		return "", fmt.Errorf("diff 内容为空，无需评审")
+	}
+
+	// 动态组装最终 System Prompt
+	systemPrompt := BuildSystemPrompt(r.customPrompt, r.repoRoot)
+	if stream && onChunk != nil {
+		err := r.client.ReviewStream(ctx, systemPrompt, diff, onChunk)
+		return "", err
+	}
+
+	return r.client.Review(ctx, systemPrompt, diff)
+}