feat(v2): add frontend remote machine integration

remote-bridge.ts adapter for machine management IPC. machines.svelte.ts
store for remote machine state. Layout store extended with
remoteMachineId on Pane interface. agent-bridge.ts and pty-bridge.ts
route to remote commands when remoteMachineId is set. SettingsDialog
gains Remote Machines section. Sidebar auto-groups remote panes by
machine label.

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

@@ -0,0 +1,122 @@
+// Remote Machine Bridge — Tauri IPC adapter for multi-machine management
+
+import { invoke } from '@tauri-apps/api/core';
+import { listen, type UnlistenFn } from '@tauri-apps/api/event';
+
+export interface RemoteMachineConfig {
+  label: string;
+  url: string;
+  token: string;
+  auto_connect: boolean;
+}
+
+export interface RemoteMachineInfo {
+  id: string;
+  label: string;
+  url: string;
+  status: string;
+  auto_connect: boolean;
+}
+
+// --- Machine management ---
+
+export async function listRemoteMachines(): Promise<RemoteMachineInfo[]> {
+  return invoke('remote_list');
+}
+
+export async function addRemoteMachine(config: RemoteMachineConfig): Promise<string> {
+  return invoke('remote_add', { config });
+}
+
+export async function removeRemoteMachine(machineId: string): Promise<void> {
+  return invoke('remote_remove', { machineId });
+}
+
+export async function connectRemoteMachine(machineId: string): Promise<void> {
+  return invoke('remote_connect', { machineId });
+}
+
+export async function disconnectRemoteMachine(machineId: string): Promise<void> {
+  return invoke('remote_disconnect', { machineId });
+}
+
+// --- Remote event listeners ---
+
+export interface RemoteSidecarMessage {
+  machineId: string;
+  sessionId?: string;
+  event?: Record<string, unknown>;
+}
+
+export interface RemotePtyData {
+  machineId: string;
+  sessionId?: string;
+  data?: string;
+}
+
+export interface RemotePtyExit {
+  machineId: string;
+  sessionId?: string;
+}
+
+export interface RemoteMachineEvent {
+  machineId: string;
+  payload?: unknown;
+  error?: unknown;
+}
+
+export async function onRemoteSidecarMessage(
+  callback: (msg: RemoteSidecarMessage) => void,
+): Promise<UnlistenFn> {
+  return listen<RemoteSidecarMessage>('remote-sidecar-message', (event) => {
+    callback(event.payload);
+  });
+}
+
+export async function onRemotePtyData(
+  callback: (msg: RemotePtyData) => void,
+): Promise<UnlistenFn> {
+  return listen<RemotePtyData>('remote-pty-data', (event) => {
+    callback(event.payload);
+  });
+}
+
+export async function onRemotePtyExit(
+  callback: (msg: RemotePtyExit) => void,
+): Promise<UnlistenFn> {
+  return listen<RemotePtyExit>('remote-pty-exit', (event) => {
+    callback(event.payload);
+  });
+}
+
+export async function onRemoteMachineReady(
+  callback: (msg: RemoteMachineEvent) => void,
+): Promise<UnlistenFn> {
+  return listen<RemoteMachineEvent>('remote-machine-ready', (event) => {
+    callback(event.payload);
+  });
+}
+
+export async function onRemoteMachineDisconnected(
+  callback: (msg: RemoteMachineEvent) => void,
+): Promise<UnlistenFn> {
+  return listen<RemoteMachineEvent>('remote-machine-disconnected', (event) => {
+    callback(event.payload);
+  });
+}
+
+export async function onRemoteStateSync(
+  callback: (msg: RemoteMachineEvent) => void,
+): Promise<UnlistenFn> {
+  return listen<RemoteMachineEvent>('remote-state-sync', (event) => {
+    callback(event.payload);
+  });
+}
+
+export async function onRemoteError(
+  callback: (msg: RemoteMachineEvent) => void,
+): Promise<UnlistenFn> {
+  return listen<RemoteMachineEvent>('remote-error', (event) => {
+    callback(event.payload);
+  });
+}