feat: initial commit - Go + CGO captcha recognition service

Features:
- Go + CGO ONNX/OpenCV wrapper for high performance
- SQLite (default) / MySQL database support
- Optional Redis caching
- JWT authentication system
- Multiple captcha recognition APIs:
  - OCR text recognition
  - Slider captcha matching
  - Image similarity comparison
  - Rotation captcha detection
  - Object detection
- React frontend with install wizard
- Docker and docker-compose support
- Gitea CI/CD pipeline

Project structure:
- cmd/server: Main entry point
- internal/: Core business logic
- pkg/onnx: ONNX Runtime CGO wrapper
- pkg/opencv: OpenCV CGO wrapper
- web/: React frontend
- deploy/: Deployment configs
- scripts/: Utility scripts

internal/middleware/auth.go

@@ -0,0 +1,96 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"anticaptcha/internal/config"
+	"anticaptcha/internal/model"
+
+	"github.com/gin-gonic/gin"
+	"github.com/golang-jwt/jwt/v5"
+)
+
+type Claims struct {
+	UserID   uint   `json:"user_id"`
+	Username string `json:"username"`
+	Role     string `json:"role"`
+	jwt.RegisteredClaims
+}
+
+func JWTAuth() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		authHeader := c.GetHeader("Authorization")
+		if authHeader == "" {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "未提供认证令牌"})
+			c.Abort()
+			return
+		}
+
+		parts := strings.Split(authHeader, " ")
+		if len(parts) != 2 || parts[0] != "Bearer" {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "认证令牌格式错误"})
+			c.Abort()
+			return
+		}
+
+		tokenString := parts[1]
+		claims := &Claims{}
+
+		token, err := jwt.ParseWithClaims(tokenString, claims, func(token *jwt.Token) (interface{}, error) {
+			return []byte(config.Cfg.JWT.Secret), nil
+		})
+
+		if err != nil || !token.Valid {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "无效的认证令牌"})
+			c.Abort()
+			return
+		}
+
+		// 将用户信息存入上下文
+		c.Set("user_id", claims.UserID)
+		c.Set("username", claims.Username)
+		c.Set("role", claims.Role)
+		c.Next()
+	}
+}
+
+func AdminOnly() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		role, exists := c.Get("role")
+		if !exists || role.(string) != "admin" {
+			c.JSON(http.StatusForbidden, gin.H{"error": "权限不足"})
+			c.Abort()
+			return
+		}
+		c.Next()
+	}
+}
+
+func GenerateToken(userID uint, username string, role string) (string, error) {
+	claims := Claims{
+		UserID:   userID,
+		Username: username,
+		Role:     role,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Duration(config.Cfg.JWT.ExpireTime) * time.Hour)),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+		},
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	return token.SignedString([]byte(config.Cfg.JWT.Secret))
+}
+
+func GetCurrentUserID(c *gin.Context) uint {
+	if id, exists := c.Get("user_id"); exists {
+		return id.(uint)
+	}
+	return 0
+}
+
+func GetCurrentUser(c *gin.Context) (*model.User, error) {
+	// 后续从数据库查询
+	return nil, nil
+}