feat: add handcrafted 8x8 sprite art and VBlank bioluminescent animation for rotten apples

include/consts.h

@@ -25,6 +25,14 @@ const uint16_t BARRIER_PAL_FILL   = 22;
 const uint16_t BARRIER_PAL_STRIPE = 23;
 const uint16_t BARRIER_PAL_WARN   = 24;
 
+// Rotten apple palette indices in SPRITE_PALETTE_SUB (animated every VBlank)
+const uint16_t ROTTEN_PAL_OUTLINE = 25; // Crisp dark outline rim
+const uint16_t ROTTEN_PAL_SKIN    = 26; // Bruised golden-amber decaying apple skin
+const uint16_t ROTTEN_PAL_DECAY   = 27; // Sunken dark necrotic rot cavity
+const uint16_t ROTTEN_PAL_MOLD    = 28; // Vivid toxic fungal green mold (animated in VBlank)
+const uint16_t ROTTEN_PAL_SPORE   = 29; // Radiant glowing spore pustule (animated in VBlank)
+const uint16_t ROTTEN_PAL_STEM    = 30; // Withered dry dead woody stem
+
 // Hard-mode temporary fatal barriers (all timings in 60 Hz VBlank frames,
 // so they stay constant in wall-clock time while the tick rate accelerates)
 const int BARRIER_START_APPLES          = 3;   // Barriers only start appearing after eating a few apples