fix: refresh tasks snapshot immediately after IPC task mutations

Previously, current_tasks.json was only written at container-start time,
so tasks created (or paused/cancelled/updated) during a session were
invisible to list_tasks until the next invocation.

Add an onTasksChanged callback to IpcDeps, called after every successful
mutation in processTaskIpc (schedule_task, pause_task, resume_task,
cancel_task, update_task). index.ts wires it up to write fresh snapshots
for all registered groups immediately, keeping no new coupling between
ipc.ts and the container layer.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ipc.ts

@@ -22,6 +22,7 @@ export interface IpcDeps {
     availableGroups: AvailableGroup[],
     registeredJids: Set<string>,
   ) => void;
+  onTasksChanged: () => void;
 }
 
 let ipcWatcherRunning = false;
@@ -270,6 +271,7 @@ export async function processTaskIpc(
           { taskId, sourceGroup, targetFolder, contextMode },
           'Task created via IPC',
         );
+        deps.onTasksChanged();
       }
       break;
 
@@ -282,6 +284,7 @@ export async function processTaskIpc(
             { taskId: data.taskId, sourceGroup },
             'Task paused via IPC',
           );
+          deps.onTasksChanged();
         } else {
           logger.warn(
             { taskId: data.taskId, sourceGroup },
@@ -300,6 +303,7 @@ export async function processTaskIpc(
             { taskId: data.taskId, sourceGroup },
             'Task resumed via IPC',
           );
+          deps.onTasksChanged();
         } else {
           logger.warn(
             { taskId: data.taskId, sourceGroup },
@@ -318,6 +322,7 @@ export async function processTaskIpc(
             { taskId: data.taskId, sourceGroup },
             'Task cancelled via IPC',
           );
+          deps.onTasksChanged();
         } else {
           logger.warn(
             { taskId: data.taskId, sourceGroup },
@@ -388,6 +393,7 @@ export async function processTaskIpc(
           { taskId: data.taskId, sourceGroup, updates },
           'Task updated via IPC',
         );
+        deps.onTasksChanged();
       }
       break;