feat(auth): add user captcha generation endpoint

- Add handler for /v1/auth/captcha/generate endpoint
- Implement captcha generation logic based on configuration
- Support local image captcha generation with Redis storage
- Return Turnstile site key for Turnstile mode
- Check EnableUserLoginCaptcha configuration

internal/handler/auth/generateCaptchaHandler.go

@@ -0,0 +1,18 @@
+package auth
+
+import (
+	"github.com/gin-gonic/gin"
+	"github.com/perfect-panel/server/internal/logic/auth"
+	"github.com/perfect-panel/server/internal/svc"
+	"github.com/perfect-panel/server/pkg/result"
+)
+
+// Generate captcha
+func GenerateCaptchaHandler(svcCtx *svc.ServiceContext) func(c *gin.Context) {
+	return func(c *gin.Context) {
+
+		l := auth.NewGenerateCaptchaLogic(c.Request.Context(), svcCtx)
+		resp, err := l.GenerateCaptcha()
+		result.HttpResult(c, resp, err)
+	}
+}