fix(billing): submit_text→submit_label, wid→self, fix indentation

- submit_label is the correct InlineForm option (not submit_text)
- Use wid:self instead of explicit widget id
- binds was incorrectly indented inside options

wwwroot/billing.ui

@@ -27,11 +27,11 @@
 						"required": true
 					}
 				],
-				"submit_text": "查询"
+				"submit_label": "查询"
 			},
 			"binds": [
 				{
-					"wid": "billing_form",
+					"wid": "self",
 					"event": "submit",
 					"actiontype": "method",
 					"target": "app.billing_tabular",