Phase 1a: focus spoofing + hook observability

Two problems surfaced in testing: (1) no way to tell whether the injected
hook was actually the input source, and (2) the final design needs the tool
window focused for Steam RPT capture, which would pause/silence games that
react to focus loss. Both are addressed here.

- Focus spoofing (hook/focus_spoof): find the game's main window, subclass it
  to rewrite/swallow WM_ACTIVATE/ACTIVATEAPP/NCACTIVATE/KILLFOCUS, and inline-
  hook GetForegroundWindow/GetActiveWindow/GetFocus to always report the game
  as active. The game keeps running and polling while unfocused.
- Status back-channel (protocol v2): the DLL reports attached/focus-spoof
  flags, game pid/hwnd, a heartbeat, and a cumulative XInputGetState counter.
  The host overlay turns the counter into a live poll rate, so "is the hook
  working" is directly observable.
- Synthetic test-input toggle in the host: forwards a known automated pattern
  (stick circle + periodic A) to prove forwarding independent of the physical
  pad.
- hook_selftest extended to assert the status channel; passes.

Documented the windowed/borderless requirement and the new observable test
flow in the README.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

host/src/ipc/ipc_server.cpp

@@ -40,6 +40,24 @@ void IpcServer::publish(const std::array<PadInfo, kMaxPads>& pads)
 	publish_pads(*block_, states, kMaxPads);
 }
 
+HookStatusView IpcServer::hook_status() const
+{
+	HookStatusView view;
+	if (block_ == nullptr)
+	{
+		return view;
+	}
+	const HookStatus& s = block_->status;
+	view.attached = s.attached != 0;
+	view.focus_spoof = s.focus_spoof != 0;
+	view.heartbeat = s.heartbeat.load(std::memory_order_relaxed);
+	view.xinput_queries = s.xinput_queries.load(std::memory_order_relaxed);
+	view.game_pid = s.game_pid;
+	view.game_hwnd = s.game_hwnd;
+	view.last_user_index = s.last_user_index;
+	return view;
+}
+
 void IpcServer::stop()
 {
 	if (block_ != nullptr)