feat: add Flutter web build support

apps/service_app/lib/ui/features/evidence/evidence_page.dart

@@ -1,5 +1,3 @@
-import 'dart:io';
-
 import 'package:flutter/material.dart';
 import 'package:image_picker/image_picker.dart';
 import 'package:uuid/uuid.dart';
@@ -44,12 +42,17 @@ class _EvidencePageState extends State<EvidencePage> {
   }
 
   Future<void> _restore() async {
-    final draft = await widget.drafts.readDraft(widget.session.identity, widget.taskIdentity);
+    final draft = await widget.drafts.readDraft(
+      widget.session.identity,
+      widget.taskIdentity,
+    );
     if (draft == null || !mounted) return;
     final values = draft['evidence'];
     if (values is List) {
       for (final value in values.whereType<Map<Object?, Object?>>()) {
-        final mapped = value.map<String, Object?>((key, item) => MapEntry(key.toString(), item));
+        final mapped = value.map<String, Object?>(
+          (key, item) => MapEntry(key.toString(), item),
+        );
         final stage = mapped['stage'] as String? ?? '';
         if (stage.isNotEmpty) _evidence[stage] = mapped;
       }
@@ -70,7 +73,7 @@ class _EvidencePageState extends State<EvidencePage> {
       accountIdentity: widget.session.identity,
       taskIdentity: widget.taskIdentity,
       stage: stage,
-      sourcePath: image.path,
+      source: image,
     );
     _evidence[stage] = {
       'stage': stage,
@@ -97,25 +100,27 @@ class _EvidencePageState extends State<EvidencePage> {
 
   Future<void> _submit() async {
     if (!_requiredStages.every(_evidence.containsKey) || _result.text.trim().isEmpty) {
-      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('请完成结果说明和全部必需取证项')));
+      ScaffoldMessenger.of(
+        context,
+      ).showSnackBar(const SnackBar(content: Text('请完成结果说明和全部必需取证项')));
       return;
     }
     setState(() => _busy = true);
-    final temporaryFiles = <String>[];
+    final temporaryFiles = <XFile>[];
     try {
       await _save();
       final inputs = <EvidenceInput>[];
       for (final item in _evidence.values) {
-        final path = await widget.drafts.materializeAttachment(
+        final file = await widget.drafts.materializeAttachment(
           accountIdentity: widget.session.identity,
           sealedName: item['sealed_name'] as String,
         );
-        temporaryFiles.add(path);
+        temporaryFiles.add(file);
         inputs.add(
           EvidenceInput(
             evidenceType: item['stage'] as String,
             mediaType: item['media_type'] as String,
-            filePath: path,
+            file: file,
             capturedAt: DateTime.parse(item['captured_at'] as String),
             requestNo: item['request_no'] as String,
           ),
@@ -127,16 +132,20 @@ class _EvidencePageState extends State<EvidencePage> {
         conclusion: _conclusion,
         evidence: inputs,
       );
-      await widget.drafts.deleteDraft(widget.session.identity, widget.taskIdentity);
+      await widget.drafts.deleteDraft(
+        widget.session.identity,
+        widget.taskIdentity,
+      );
       if (mounted) Navigator.pop(context, true);
     } catch (error) {
       if (mounted) {
-        ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text('提交失败，草稿仍安全保留：$error')));
+        ScaffoldMessenger.of(
+          context,
+        ).showSnackBar(SnackBar(content: Text('提交失败，草稿仍安全保留：$error')));
       }
     } finally {
-      for (final path in temporaryFiles) {
-        final file = File(path);
-        if (file.existsSync()) await file.delete();
+      for (final file in temporaryFiles) {
+        await widget.drafts.discardMaterializedAttachment(file);
       }
       if (mounted) setState(() => _busy = false);
     }