fix(resolve): release cancelled previews and preserve task ownership

ui/flutter/lib/core/capabilities/app_capabilities.dart

@@ -93,6 +93,10 @@ void _bindGopeed(CapabilityRegistry registry, _ConfigStore configStore) {
       (p) => api.getMirrorCandidates(p['provider'] as String, p['url'] as String),
     )
     ..bind(GopeedMethods.resolve, api.resolve)
+    ..bind(GopeedMethods.releaseResolve, (id) async {
+      await api.releaseResolve(id);
+      return const RpcUnit();
+    })
     ..bind(GopeedMethods.createTask, api.createTask)
     ..bind(GopeedMethods.createTaskBatch, api.createTaskBatch)
     ..bind(GopeedMethods.patchTask, (params) async {

ui/flutter/lib/core/capabilities/gopeed_capability.dart

@@ -16,6 +16,7 @@ abstract final class GopeedMethods {
   static const triggerProtocolJob = RpcMethod<Map<String, dynamic>, RpcUnit>('gopeed.protocol.job.trigger');
   static const getMirrorCandidates = RpcMethod<Map<String, dynamic>, List<String>>('gopeed.mirrors.candidates');
   static const resolve = RpcMethod<ResolveTask, ResolveResult>('gopeed.resolve');
+  static const releaseResolve = RpcMethod<String, RpcUnit>('gopeed.releaseResolve');
   static const createTask = RpcMethod<CreateTask, String>('gopeed.task.create');
   static const createTaskBatch = RpcMethod<CreateTaskBatch, CreateTaskBatchResult>('gopeed.task.createBatch');
   static const patchTask = RpcMethod<Map<String, dynamic>, RpcUnit>('gopeed.task.patch');
@@ -50,6 +51,7 @@ class GopeedService {
   Future<List<String>> getMirrorCandidates(String provider, String url) =>
       _invoker.invoke(GopeedMethods.getMirrorCandidates, {'provider': provider, 'url': url});
   Future<ResolveResult> resolve(ResolveTask request) => _invoker.invoke(GopeedMethods.resolve, request);
+  Future<void> releaseResolve(String id) async => _invoker.invoke(GopeedMethods.releaseResolve, id);
 
   Future<String> createTask(CreateTask request) => _invoker.invoke(GopeedMethods.createTask, request);