管理员默认密码 admin/admin，首次登录强制改密码；增加服务器部署配置

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/backend/internal/config/config.go

@@ -11,8 +11,6 @@ type Config struct {
 	DatabaseURL    string
 	AuthDBPath     string
 	JWTSecret      []byte
-	AdminUser      string
-	AdminPass      string
 	TushareAPIURL  string
 }
 
@@ -21,8 +19,6 @@ func Load() (*Config, error) {
 		ListenAddr:    getenv("LISTEN_ADDR", ":8080"),
 		DatabaseURL:   os.Getenv("DATABASE_URL"),
 		AuthDBPath:    getenv("AUTH_DB_PATH", "/app/auth/auth.db"),
-		AdminUser:     strings.TrimSpace(os.Getenv("ADMIN_USER")),
-		AdminPass:     os.Getenv("ADMIN_PASS"),
 		TushareAPIURL: getenv("TUSHARE_API_URL", "http://tushare:8000"),
 	}
 	if cfg.DatabaseURL == "" {