Detect terminated / hung target and reflect it in the UI

The Injection panel kept showing "Attached" after the game exited. Now it tracks
target liveness each frame (InjectionPanel::tick from the main loop, independent of
panel visibility):
- a SYNCHRONIZE|QUERY process handle taken at inject time -> WaitForSingleObject
  detects the process exiting (Terminated);
- the hook heartbeat stalling for ~2 s while the process still exists flags a
  distinct Hung state (games here can freeze without exiting).

The panel shows a clear colored banner per state and disables the subsystem
hook/unhook controls and the synthetic-input toggle when the target isn't alive.
game_hwnd() returns null once Terminated, so the Video and Audio panels drop to
idle instead of chasing a dead window.

Verified: x64 build + ctest 7/7 green; host launches and renders the panels without
regression (screenshot smoke test). The interactive terminated/hung visual against a
real game is best confirmed in a live session (ImGui injection can't be GUI-scripted).

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

host/src/main.cpp

@@ -145,6 +145,7 @@ int run()
 #endif
 		input->poll();
 		injection.publish(input->pads());
+		injection.tick(); // refresh target liveness before the mirror panels read game_hwnd()
 		const HWND game = injection.game_hwnd();
 		capture.set_target(game);
 		audio.set_target(game);