nost: touch piano mode (#830)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Touch piano mode. Allows piano keys to be played with the touch screen.
Since the touch screen is still needed for menu navigation (including
during songs) a toggle switch is added so that the user can flip between
navigation mode and piano mode.

The touch targets are pixel-perfect. Don't let the game's piano
animations fool you.

## Testing

src/spice2x/acio/panb/panb.cpp

@@ -3,6 +3,7 @@
 #include "rawinput/rawinput.h"
 #include "games/nost/io.h"
 #include "games/nost/nost.h"
+#include "games/nost/touch_mode.h"
 #include "util/logging.h"
 #include "avs/game.h"
 
@@ -16,6 +17,7 @@ using namespace GameAPI;
 // static stuff
 static uint8_t STATUS_BUFFER[277];
 static bool STATUS_BUFFER_FREEZE = false;
+static constexpr uint8_t NOST_TOUCH_PIANO_VELOCITY = 11;
 
 /*
  * Implementations
@@ -226,6 +228,8 @@ static bool __cdecl ac_io_panb_update_control_status_buffer() {
                 games::nost::Analogs::Key27, games::nost::Analogs::Key28,
         };
 
+        const auto touch_key_state = games::nost::touch_mode::piano_key_state();
+
         // iterate pairs of keys
         for (size_t key_pair = 0; key_pair < 28 / 2; key_pair++) {
 
@@ -257,6 +261,10 @@ static bool __cdecl ac_io_panb_update_control_status_buffer() {
             if (button0 > 0) {
                 state0 = button0;
             }
+            if ((touch_key_state & (UINT32_C(1) << (key_pair * 2))) &&
+                state0 < NOST_TOUCH_PIANO_VELOCITY) {
+                state0 = NOST_TOUCH_PIANO_VELOCITY;
+            }
 
             const auto button1 = panb_get_button_velocity(
                 buttons.at(button_mapping[key_pair * 2 + 1]),
@@ -267,6 +275,10 @@ static bool __cdecl ac_io_panb_update_control_status_buffer() {
             if (button1 > 0) {
                 state1 = button1;
             }
+            if ((touch_key_state & (UINT32_C(1) << (key_pair * 2 + 1))) &&
+                state1 < NOST_TOUCH_PIANO_VELOCITY) {
+                state1 = NOST_TOUCH_PIANO_VELOCITY;
+            }
 
             // build value
             uint8_t value = 0;