feat(remote): wake a sleeping host from user input (Wake-on-LAN)

A durable remote session survives SSH drops (COD-104/108), but nothing brought
the HOST back: after the remote machine suspended, the local tmux pane's ssh
child stalled silently and `send-keys` SUCCEEDS against it, so typed input
vanished with no error anywhere.

Add an optional per-host `wakeCommand` (Wake-on-LAN wrapper, e.g. whuff) that
the input route runs when a wake-enabled host is unreachable: input is buffered,
the host is woken, the pane is reattached, and the buffer is flushed in order.
Detection is a throttled bare TCP probe on wake-enabled hosts only, and only
REAL user input may wake a host - the auto-reconnect watcher and boot recovery
deliberately cannot, or the host would be re-woken seconds after every suspend
and could never stay asleep.

test/mocks/mock-session.ts

@@ -96,6 +96,14 @@ export class MockSession extends EventEmitter {
     return true;
   }
 
+  /**
+   * Mirrors `Session.reattachRemote()` — the COD-108 transport re-establish that
+   * the wake-on-LAN flow calls once a sleeping host is back. Defaults to success;
+   * set `reattachRemote.mockResolvedValue(false)` to model a pane that could not
+   * be respawned.
+   */
+  reattachRemote = vi.fn(async (): Promise<boolean> => true);
+
   /** Exactly-once input dedup — mirrors Session.shouldApplyInput so route tests
    *  exercising the reliable-delivery path behave like production. */
   private _appliedInputSeq = new Map<string, number>();