feat: 合同附件支持拖拽上传

drop_zone: 虚线边框拖放区域, 点击选择文件
Form: 隐藏字段 folderid+fiid + file input
Script: dragover/drop 事件处理, 拖入文件自动上传

wwwroot/api/contract_attach.ui

@@ -30,35 +30,74 @@
                 },
                 {
                     "widgettype": "Filler"
-                },
-                {
-                    "widgettype": "Button",
-                    "options": {
-                        "label": "上传附件",
-                        "css": "primary",
-                        "borderRadius": "6px",
-                        "padding": "4px 12px"
-                    },
-                    "binds": [{
-                        "wid": "self",
-                        "event": "click",
-                        "actiontype": "urlwidget",
-                        "target": "PopupWindow",
-                        "popup_options": {
-                            "title": "上传附件",
-                            "width": "450px",
-                            "height": "200px",
-                            "dismiss_events": ["cancel"]
-                        },
-                        "options": {
-                            "url": "{{entire_url('/filemgr/upload_file.ui')}}?id={{folder}}&fiid={{fiid}}"
-                        }
-                    }]
                 }
             ]
         },
+        {
+            "widgettype": "VBox",
+            "id": "drop_zone",
+            "options": {
+                "css": "card",
+                "width": "100%",
+                "height": "80px",
+                "padding": "16px",
+                "bgcolor": "#1E293B",
+                "border": "2px dashed #475569",
+                "borderRadius": "8px",
+                "alignItems": "center",
+                "justifyContent": "center",
+                "marginBottom": "12px"
+            },
+            "subwidgets": [
+                {
+                    "widgettype": "Text",
+                    "options": {
+                        "otext": "拖拽文件到此处上传，或点击选择文件",
+                        "i18n": true,
+                        "color": "#94A3B8",
+                        "fontSize": "13px"
+                    }
+                },
+                {
+                    "widgettype": "Form",
+                    "id": "upload_form",
+                    "options": {
+                        "fields": [
+                            {"name": "folderid", "uitype": "hide", "value": "{{folder}}"},
+                            {"name": "fiid", "uitype": "hide", "value": "{{fiid}}"},
+                            {"name": "upfile", "uitype": "file", "label": ""}
+                        ]
+                    },
+                    "binds": [{
+                        "wid": "self",
+                        "event": "submited",
+                        "actiontype": "urlwidget",
+                        "target": "self",
+                        "options": {
+                            "url": "{{entire_url('/filemgr/upload_file.dspy')}}"
+                        }
+                    }]
+                }
+            ],
+            "binds": [{
+                "wid": "self",
+                "event": "click",
+                "actiontype": "method",
+                "target": "upload_form",
+                "method": "select_file"
+            }]
+        },
+        {
+            "widgettype": "Script",
+            "id": "drop_handler",
+            "options": {
+                "script": "var dz=document.querySelector('#drop_zone'); if(dz){dz.addEventListener('dragover',function(e){e.preventDefault();e.stopPropagation();this.style.borderColor='#3B82F6';});dz.addEventListener('dragleave',function(e){e.preventDefault();e.stopPropagation();this.style.borderColor='#475569';});dz.addEventListener('drop',function(e){e.preventDefault();e.stopPropagation();this.style.borderColor='#475569';var dt=e.dataTransfer;if(!dt.files.length)return;var fi=bricks.app.getWidgetById('upload_form');if(fi&&fi.widgets&&fi.widgets[2]){fi.widgets[2].files=dt.files;fi.widgets[2]._onchange();}});}"
+            },
+            "binds": []
+        },
         {
             "widgettype": "Tabular",
+            "id": "attach_tbl",
             "options": {
                 "css": "card",
                 "width": "100%",