feat(v2): refactor reconnection probe to TCP-only and add frontend listeners

Replace attempt_ws_connect() with attempt_tcp_probe() in RemoteManager to
avoid allocating per-connection resources (PtyManager, SidecarManager) on
the relay during reconnection probes. Add onRemoteMachineReconnecting and
onRemoteMachineReconnectReady event listeners in remote-bridge.ts. Wire
machines store to auto-reconnect when relay becomes reachable.

v2/src/lib/adapters/remote-bridge.ts

@@ -120,3 +120,24 @@ export async function onRemoteError(
     callback(event.payload);
   });
 }
+
+export interface RemoteReconnectingEvent {
+  machineId: string;
+  backoffSecs: number;
+}
+
+export async function onRemoteMachineReconnecting(
+  callback: (msg: RemoteReconnectingEvent) => void,
+): Promise<UnlistenFn> {
+  return listen<RemoteReconnectingEvent>('remote-machine-reconnecting', (event) => {
+    callback(event.payload);
+  });
+}
+
+export async function onRemoteMachineReconnectReady(
+  callback: (msg: RemoteMachineEvent) => void,
+): Promise<UnlistenFn> {
+  return listen<RemoteMachineEvent>('remote-machine-reconnect-ready', (event) => {
+    callback(event.payload);
+  });
+}

v2/src/lib/stores/machines.svelte.ts

@@ -9,6 +9,8 @@ import {
   onRemoteMachineReady,
   onRemoteMachineDisconnected,
   onRemoteError,
+  onRemoteMachineReconnecting,
+  onRemoteMachineReconnectReady,
   type RemoteMachineConfig,
   type RemoteMachineInfo,
 } from '../adapters/remote-bridge';
@@ -94,4 +96,22 @@ export async function initMachineListeners(): Promise<void> {
       notify('error', `Error from ${machine.label}: ${msg.error}`);
     }
   });
+
+  await onRemoteMachineReconnecting((msg) => {
+    const machine = machines.find(m => m.id === msg.machineId);
+    if (machine) {
+      machine.status = 'reconnecting';
+      notify('info', `Reconnecting to ${machine.label} in ${msg.backoffSecs}s…`);
+    }
+  });
+
+  await onRemoteMachineReconnectReady((msg) => {
+    const machine = machines.find(m => m.id === msg.machineId);
+    if (machine) {
+      notify('info', `${machine.label} reachable — reconnecting…`);
+      connectMachine(msg.machineId).catch((e) => {
+        notify('error', `Auto-reconnect failed for ${machine.label}: ${e}`);
+      });
+    }
+  });
 }