feat:增加朋友圈表单功能

lib/widgets/common/form.dart

@@ -4,7 +4,7 @@ import 'package:flutter/material.dart';
 InputDecoration buildInputDecoration({
   required BuildContext context,
   required String hintText,
-  required IconData prefixIcon,
+  IconData? prefixIcon,
 }) {
   final colors = Theme.of(context).colorScheme;
 
@@ -27,7 +27,10 @@ InputDecoration buildInputDecoration({
     ),
     contentPadding: const EdgeInsets.symmetric(horizontal: 15, vertical: 14),
     errorStyle: const TextStyle(fontSize: 12, height: 1, color: Colors.red),
-    prefixIcon: Icon(prefixIcon, size: 20, color: Color(0xFF86909C)),
+    prefixIcon:
+        prefixIcon != null
+            ? Icon(prefixIcon, size: 20, color: Color(0xFF86909C))
+            : null,
     prefixIconConstraints: const BoxConstraints(minWidth: 40),
     isDense: true,
   );