Add a main menu scene with Start/Hard Mode/Music options

The game now boots into a menu (Start Game, Hard Mode toggle, Music
toggle) navigated with Up/Down and A/Start, instead of dropping
straight into a match. B returns to the menu from a paused or
game-over state.

source/game_render.cpp

@@ -143,9 +143,14 @@ void draw_stats(const GameState &state, bool internals, bool musicEnabled, uint8
     }
 
     if (!state.paused) {
+        if (state.gameOver) {
+            iprintf("\x1b[23;0HB = Main Menu");
+        }
         return;
     }
 
+    iprintf("\x1b[21;0HB = Main Menu");
+
     if (musicEnabled) {
         iprintf("\x1b[23;0HX = Disable Music");
     } else {
@@ -159,6 +164,30 @@ void draw_stats(const GameState &state, bool internals, bool musicEnabled, uint8
     }
 }
 
+void draw_menu(const GameState &state, const RenderAssets &assets, bool musicEnabled) {
+    oamClear(&oamSub, 0, 0);
+    oamUpdate(&oamSub);
+
+    consoleSelect(assets.bottomScreen);
+    consoleClear();
+
+    consoleSelect(assets.topScreen);
+    consoleClear();
+
+    iprintf("\x1b[3;10HSNAKE PLUS");
+    iprintf("\x1b[5;5H---------------------");
+
+    const char *hardModeLabel = state.hardMode ? "ON " : "OFF";
+    const char *musicLabel = musicEnabled ? "ON " : "OFF";
+
+    iprintf("\x1b[8;7H%c Start Game", state.menuSelection == 0 ? '>' : ' ');
+    iprintf("\x1b[10;7H%c Hard Mode: %s", state.menuSelection == 1 ? '>' : ' ', hardModeLabel);
+    iprintf("\x1b[12;7H%c Music: %s", state.menuSelection == 2 ? '>' : ' ', musicLabel);
+
+    iprintf("\x1b[19;3HUP/DOWN: Navigate");
+    iprintf("\x1b[20;3HA/START: Select");
+}
+
 void blink_apples(const GameState &state, u16 *gfx_apple) {
     if (state.ticks % 4) {
         dmaCopy(get_sprite_pointer(5), gfx_apple, 64);