Initial open-source release (MIT): image2api AI gateway

Full Go backend + Vue 3 frontend, OpenAI-compatible API, multi-provider
account pools, billing/admin, Docker one-command deploy with auto HTTPS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/internal/http/middleware/request_id.go

@@ -0,0 +1,20 @@
+package middleware
+
+import (
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+)
+
+const requestIDKey = "request_id"
+
+func RequestID() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		reqID := c.GetHeader("X-Request-Id")
+		if reqID == "" {
+			reqID = uuid.NewString()
+		}
+		c.Set(requestIDKey, reqID)
+		c.Writer.Header().Set("X-Request-Id", reqID)
+		c.Next()
+	}
+}