Check previously-ignored injection / capture / rumble return values

- injector bitness gate: IsWow64Process2 failure was treated as "native", which
  would send the x64 DLL into a 32-bit target. Fall back to the legacy
  IsWow64Process before giving up to permissive.
- injector helper exit: GetExitCodeProcess's BOOL was ignored; on a failed query
  surface GetLastError instead of a misleading exit code.
- window_capture: CreateShaderResourceView's HRESULT was ignored, and width_/
  height_ were committed even on failure, so the (latest_ == nullptr) recreate
  guard never retried -- a silently black mirror until the next resize. Only
  commit the dims on success; otherwise drop latest_ so the next frame retries.
- xinput rumble: make the best-effort XInputSetState ignore explicit (a
  disconnected pad re-syncs on the next refresh; the result isn't actionable).

The GetClientRect/ClientToScreen reads in mkb_forward are left as-is: a failure
there is a single self-correcting frame (the mapping is rejected and reused next
frame), so checking them adds no actionable behavior.

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

host/src/input/xinput_source.cpp

@@ -46,7 +46,9 @@ void XInputSource::set_rumble(int slot, std::uint16_t left, std::uint16_t right)
 		return;
 	}
 	XINPUT_VIBRATION v{left, right};
-	XInputSetState(static_cast<DWORD>(slot), &v);
+	// Best-effort: if the device just disconnected this returns ERROR_DEVICE_NOT_CONNECTED, but rumble
+	// is fire-and-forget (the next connected-pad refresh re-syncs state), so the result isn't acted on.
+	(void)XInputSetState(static_cast<DWORD>(slot), &v);
 }
 
 } // namespace coop