feat(remote): host-unreachable banner, manual wake, and native MAC wake-on-LAN

The reactive wake (typing into a session whose host slept) left the state invisible:
nothing told the user the machine was asleep, and with no wake target configured
there was nothing to do about it. Adds:

- RemoteHost.wakeMac (comma-separated) - Codeman builds and broadcasts the magic
  packet itself (UDP port 9), so the common case needs no external script. The
  existing wakeCommand stays as the explicit override.
- GET /api/sessions/:id/reachability - probes (throttled, cached, and it never
  wakes) and reports HOW the host can be woken, or that nothing is configured.
- POST /api/sessions/:id/wake - wakes, waits, reattaches the pane and flushes
  buffered input; 400 with a routable message when no target is configured.
- The amber host-unreachable banner + its 'Wake' / 'Configure WoL' action, and a
  small config dialog that saves via PUT /api/remote-hosts/:id.
- RemoteWakeDeps.resolveRemote: host config is re-resolved for LIVE sessions
  (throttled + cached), so saving the dialog takes effect without a restart.

src/web/public/app.js

@@ -221,7 +221,6 @@ const _SSE_HANDLER_MAP = [
   [SSE_EVENTS.REMOTE_RECONNECT_EXHAUSTED, '_onRemoteReconnectExhausted'],
   [SSE_EVENTS.REMOTE_HOST_WAKING, '_onRemoteHostWaking'],
   [SSE_EVENTS.REMOTE_HOST_WAKE_FAILED, '_onRemoteHostWakeFailed'],
-
   // Ralph
   [SSE_EVENTS.SESSION_RALPH_LOOP_UPDATE, '_onRalphLoopUpdate'],
   [SSE_EVENTS.SESSION_RALPH_TODO_UPDATE, '_onRalphTodoUpdate'],
@@ -6076,6 +6075,9 @@ class CodemanApp {
     // bar (issue #262). Also disarms a one-shot Ctrl left over from the tab we
     // just left, so it can never fire against the session we just opened.
     if (typeof KeyboardAccessoryBar !== 'undefined') KeyboardAccessoryBar.refreshForActiveSession();
+    // Remote-host reachability banner: only meaningful for a remote session, so this
+    // also clears it when the newly active tab is local.
+    this.refreshHostWakeBanner?.(sessionId);
 
     // Restore flushed offset AND text IMMEDIATELY so backspace/typing work during
     // the async buffer load.  Without this, the offset is 0 during the