feat: implement core functionality for super-frpc service

This commit introduces the core functionality for the super-frpc service including:
- Configuration management
- User authentication and authorization
- Database integration
- FRPC instance management
- API endpoints for user operations
- Token-based authentication system
- Password hashing and validation

config.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+)
+
+type Config struct {
+	ListenAddr   string `json:"listenAddr"`
+	ListenPort   string `json:"listenPort"`
+	FrpcPath     string `json:"frpcPath"`
+	InstancePath string `json:"instancePath"`
+	Debug        bool   `json:"debug"`
+}
+
+var globalConfig *Config
+
+func LoadConfig(configPath string) (*Config, error) {
+	data, err := os.ReadFile(configPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read config file: %w", err)
+	}
+
+	var config Config
+	if err := json.Unmarshal(data, &config); err != nil {
+		return nil, fmt.Errorf("failed to parse config file: %w", err)
+	}
+
+	if config.ListenAddr == "" {
+		config.ListenAddr = "0.0.0.0"
+	}
+
+	if config.ListenPort == "" {
+		config.ListenPort = "8080"
+	}
+
+	if config.FrpcPath == "" {
+		config.FrpcPath = "/usr/bin/frpc"
+	}
+
+	if config.InstancePath == "" {
+		config.InstancePath = "./configs"
+	}
+
+	if err := os.MkdirAll(config.InstancePath, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create config directory: %w", err)
+	}
+
+	globalConfig = &config
+	return &config, nil
+}
+
+func GetConfig() (*Config, error) {
+	if globalConfig == nil {
+		return nil, errors.New("config not loaded")
+	}
+	return globalConfig, nil
+}
+
+func SaveConfig(configPath string, config *Config) error {
+	data, err := json.MarshalIndent(config, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal config: %w", err)
+	}
+
+	if err := os.WriteFile(configPath, data, 0644); err != nil {
+		return fmt.Errorf("failed to write config file: %w", err)
+	}
+
+	globalConfig = config
+	return nil
+}