fix: Text widgets use 'text' not 'label', Button widgets use 'label' not 'text

Per bricks-framework specification:
- Text/Title controls: use 'text' for non-i18n text, 'otext'+'i18n:true' for i18n
- Button controls: use 'label' for button display text

wwwroot/index.ui

@@ -26,12 +26,12 @@
                 {
                     "widgettype": "Text",
                     "options": {
-            "label": "CRM系统",
                         "style": {
                             "fontSize": "20px",
                             "fontWeight": "bold",
                             "color": "white"
-            }
+                        },
+                        "text": "CRM系统"
                     }
                 },
                 {
@@ -42,11 +42,11 @@
                     "widgettype": "Text",
                     "id": "lbl_username",
                     "options": {
-            "label": "用户: admin",
                         "style": {
                             "color": "white",
                             "marginRight": "16px"
-            }
+                        },
+                        "text": "用户: admin"
                     }
                 },
                 {

wwwroot/login.ui

@@ -26,14 +26,14 @@
                 {
                     "widgettype": "Text",
                     "options": {
-            "label": "CRM系统登录",
                         "style": {
                             "fontSize": "24px",
                             "fontWeight": "bold",
                             "textAlign": "center",
                             "marginBottom": "24px",
                             "color": "#333"
-            }
+                        },
+                        "text": "CRM系统登录"
                     }
                 },
                 {