feat: surfing minigame overhaul + authentic Game Corner rendering

Surfing minigame:
- Add title screen (ROUTINE_TITLE) with Pikachu intro, logo banner, instructions
- Add GLSL HBlank wave distortion shader, OAM water spray/splash sprites
- Add multi-path asset loader, isMinigame/isFixedSpeed flags, crash recovery fixes
- Extract SurfingPikachu graphics + composite title_bg.png from ROM

Game Corner (built visual layer from ROM assets; logic existed, rendering was placeholder):
- SlotMachine: GBC tilemap background, authentic reel symbol sprites, Golem/Chansey
  near-miss animations, lit/unlit lights, payout panel
- CardFlip: GBC tilemap board, hardware-accurate card flip sequence, OAM cursor frame
- RomExtractorGen2: extract slots + card_flip sprite sheets and tilemaps

Tests: SurfingMinigame units 8-13; 500-spin SlotMachine and 500-hand CardFlip stress tests

src/core/Music.lua

@@ -230,7 +230,7 @@ end
 
 function Music.play(data, song, loop, ctx)
   if not song then return end
-  if not love.audio then return end -- headless test stub
+  if not (love and love.audio) then return end -- headless test stub
   ctx = ctx or {}
   song = selectSong(song, ctx)