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/config/config.go

@@ -0,0 +1,112 @@
+package config
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/viper"
+)
+
+type Config struct {
+	Server   ServerConfig
+	Database DatabaseConfig
+	Redis    RedisConfig
+	JWT      JWTConfig
+	Captcha  CaptchaConfig
+}
+
+type ServerConfig struct {
+	Host string
+	Port int
+	Mode string
+}
+
+type DatabaseConfig struct {
+	Type     string // sqlite or mysql
+	Host     string
+	Port     int
+	User     string
+	Password string
+	Database string
+	SQLite   SQLiteConfig
+}
+
+type SQLiteConfig struct {
+	Path string
+}
+
+type RedisConfig struct {
+	Enabled  bool
+	Host     string
+	Port     int
+	Password string
+	DB       int
+}
+
+type JWTConfig struct {
+	Secret     string
+	ExpireTime int // hours
+}
+
+type CaptchaConfig struct {
+	ModelPath string
+}
+
+var Cfg *Config
+
+func Load(configPath string) error {
+	viper.SetConfigName("config")
+	viper.SetConfigType("yaml")
+	viper.AddConfigPath(".")
+	viper.AddConfigPath("./data")
+	viper.AddConfigPath(configPath)
+
+	// 默认值
+	viper.SetDefault("server.host", "0.0.0.0")
+	viper.SetDefault("server.port", 6688)
+	viper.SetDefault("server.mode", "release")
+	viper.SetDefault("database.type", "sqlite")
+	viper.SetDefault("database.sqlite.path", "./data/app.db")
+	viper.SetDefault("database.host", "localhost")
+	viper.SetDefault("database.port", 3306)
+	viper.SetDefault("redis.enabled", false)
+	viper.SetDefault("redis.host", "localhost")
+	viper.SetDefault("redis.port", 6379)
+	viper.SetDefault("redis.db", 0)
+	viper.SetDefault("jwt.expire_time", 1440) // 60 days
+	viper.SetDefault("captcha.model_path", "./models")
+
+	if err := viper.ReadInConfig(); err != nil {
+		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
+			return fmt.Errorf("配置文件未找到，请先运行安装向导")
+		}
+		return err
+	}
+
+	Cfg = &Config{}
+	if err := viper.Unmarshal(Cfg); err != nil {
+		return err
+	}
+
+	// 从环境变量读取 JWT Secret
+	if secret := os.Getenv("JWT_SECRET"); secret != "" {
+		Cfg.JWT.Secret = secret
+	}
+
+	return nil
+}
+
+func Save(cfg *Config) error {
+	viper.Set("server", cfg.Server)
+	viper.Set("database", cfg.Database)
+	viper.Set("redis", cfg.Redis)
+	viper.Set("jwt", cfg.JWT)
+	viper.Set("captcha", cfg.Captcha)
+
+	return viper.WriteConfig()
+}
+
+func IsInstalled() bool {
+	_, err := os.Stat("./data/config.yaml")
+	return err == nil
+}