Phase 1a: per-slot poll viz + input-path diagnostics

Surfaced by a game (Life is Strange: Before the Storm) that ignores
controller input when it lacks true OS focus even though it still polls
XInput. To find the focus-gated detection path, instrument the hook.

Protocol v3 status back-channel now reports:
- per-slot XInputGetState and XInputGetCapabilities counters (replacing the
  single aggregate), so the overlay shows exactly which slots the game polls
  and how fast;
- focus-API call counts (GetForegroundWindow/GetActiveWindow/GetFocus) to see
  whether the game consults the APIs we spoof;
- input-path diagnostics: whether the process registered Raw Input for a
  gamepad usage and whether it set RIDEV_INPUTSINK (background delivery), and
  whether a DirectInput dll is loaded.

Host overlay gains a per-slot poll table and an "Input path" section. The DLL
refreshes input diagnostics each worker tick via GetRegisteredRawInputDevices.
hook_selftest updated for per-slot counters; passes.

This is diagnostic-only: once a real run shows which path LiS uses, the
targeted focus fix (e.g. forcing RIDEV_INPUTSINK or DI background coop) follows.

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

host/src/ipc/ipc_server.hpp

@@ -18,10 +18,15 @@ struct HookStatusView
 	bool attached = false;       // XInput hooks installed in the game
 	bool focus_spoof = false;    // focus spoofing active
 	std::uint32_t heartbeat = 0; // DLL liveness counter
-	std::uint64_t xinput_queries = 0;
+	std::uint64_t get_state[kMaxPads] = {};
+	std::uint64_t get_caps[kMaxPads] = {};
+	std::uint64_t focus_calls[FocusApi_Count] = {};
 	std::uint32_t game_pid = 0;
 	std::uint64_t game_hwnd = 0;
-	std::uint32_t last_user_index = 0;
+	bool raw_input_registered = false;
+	bool raw_input_gamepad = false;
+	bool raw_input_gamepad_sink = false;
+	bool dinput_loaded = false;
 };
 
 class IpcServer