feat: 添加对 @Bind 注释中 model 字段的支持，优化路径参数绑定逻辑并更新文档

pkg/ast/route/builder.go

@@ -85,31 +85,41 @@ func buildRenderData(opts RenderBuildOpts) (RenderData, error) {
 }
 
 func buildParamToken(item ParamDefinition) string {
-	key := item.Name
-	if item.Key != "" {
-		key = item.Key
-	}
+    key := item.Name
+    if item.Key != "" {
+        key = item.Key
+    }
 
-	switch item.Position {
-	case PositionQuery:
-		return fmt.Sprintf(`Query%s[%s]("%s")`, scalarSuffix(item.Type), item.Type, key)
-	case PositionHeader:
-		return fmt.Sprintf(`Header[%s]("%s")`, item.Type, key)
-	case PositionFile:
-		return fmt.Sprintf(`File[multipart.FileHeader]("%s")`, key)
-	case PositionCookie:
-		if item.Type == "string" {
-			return fmt.Sprintf(`CookieParam("%s")`, key)
-		}
-		return fmt.Sprintf(`Cookie[%s]("%s")`, item.Type, key)
-	case PositionBody:
-		return fmt.Sprintf(`Body[%s]("%s")`, item.Type, key)
-	case PositionPath:
-		return fmt.Sprintf(`Path%s[%s]("%s")`, scalarSuffix(item.Type), item.Type, key)
-	case PositionLocal:
-		return fmt.Sprintf(`Local[%s]("%s")`, item.Type, key)
-	}
-	return ""
+    switch item.Position {
+    case PositionQuery:
+        return fmt.Sprintf(`Query%s[%s]("%s")`, scalarSuffix(item.Type), item.Type, key)
+    case PositionHeader:
+        return fmt.Sprintf(`Header[%s]("%s")`, item.Type, key)
+    case PositionFile:
+        return fmt.Sprintf(`File[multipart.FileHeader]("%s")`, key)
+    case PositionCookie:
+        if item.Type == "string" {
+            return fmt.Sprintf(`CookieParam("%s")`, key)
+        }
+        return fmt.Sprintf(`Cookie[%s]("%s")`, item.Type, key)
+    case PositionBody:
+        return fmt.Sprintf(`Body[%s]("%s")`, item.Type, key)
+    case PositionPath:
+        // If a model field is specified, generate a model-lookup binder from path value.
+        if item.ModelField != "" || item.Model != "" {
+            field := item.ModelField
+            if field == "" {
+                field = "id"
+            }
+            // PathModel is expected to resolve the path param to the specified model by field.
+            // Example: PathModel[models.User]("id", "user_id")
+            return fmt.Sprintf(`PathModel[%s]("%s", "%s")`, item.Type, field, key)
+        }
+        return fmt.Sprintf(`Path%s[%s]("%s")`, scalarSuffix(item.Type), item.Type, key)
+    case PositionLocal:
+        return fmt.Sprintf(`Local[%s]("%s")`, item.Type, key)
+    }
+    return ""
 }
 
 func scalarSuffix(t string) string {