feat: add finite lifetimes and despawn mechanics for rotten and cursed apples

include/consts.h

@@ -8,6 +8,12 @@ const int START_LENGTH_HARD = 2;
 const int APPLE_SCORE = 10;
 const int CURSE_DURATION_TICKS = 40;
 
+// Evil item lifetimes (in game ticks, so density stays balanced across speed scaling)
+const int BAD_APPLE_LIFETIME_TICKS    = 80; // Rotten apple lasts 80 ticks (~8 spawn cycles)
+const int CURSED_APPLE_LIFETIME_TICKS = 90; // Cursed apple lasts 90 ticks before despawning
+const int EVIL_ITEM_BLINK_TICKS       = 20; // Last 20 ticks: flashes to warn player of imminent despawn
+const int EVIL_ITEM_FAST_BLINK_TICKS  = 8;  // Last 8 ticks: rapid strobe before disappearing
+
 // Cursed apple palette indices in SPRITE_PALETTE_SUB
 const uint16_t CURSE_PAL_OUTLINE = 16;
 const uint16_t CURSE_PAL_FILL    = 17;

include/game_logic.h

@@ -12,6 +12,7 @@ void spawn_apples(GameState &state);
 void spawn_apples_rotten(GameState &state);
 void spawn_apples_cursed(GameState &state);
 void tick_status_effects(GameState &state);
+void tick_evil_items(GameState &state);
 
 uint8_t calculate_intensity_31(const GameState &state);
 uint16_t calculate_timer_freq_mhz(const GameState &state);

include/game_state.h

@@ -32,6 +32,13 @@ struct Barrier {
     uint16_t framesLeft = 0; // Frames remaining in the current phase
 };
 
+// Evil item (rotten apple or cursed apple) with position and lifetime in game ticks
+struct EvilItem {
+    int8_t x = 0;
+    int8_t y = 0;
+    uint16_t ticksRemaining = 0;
+};
+
 struct GameState {
     volatile uint16_t ticks = 0;
     volatile uint16_t snakelength = 0;
@@ -55,8 +62,8 @@ struct GameState {
 
     std::deque<std::array<int, 3>> snake;
     std::vector<std::array<int, 2>> apples;
-    std::vector<std::array<int, 2>> bad_apples;
-    std::vector<std::array<int, 2>> cursed_apples;
+    std::vector<EvilItem> bad_apples;
+    std::vector<EvilItem> cursed_apples;
 };
 
 #endif