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

tests/test_surfing_minigame.lua

@@ -40,14 +40,16 @@ local mockGame = {
 
 print("Running SurfingMinigame unit tests...")
 
--- Test 1: Initialization
+-- Test 1: Initialization & Title Screen transition
 local mg = SurfingMinigame.new(mockGame)
+assert_eq(mg.routine, -1, "Initial routine must be ROUTINE_TITLE (-1)")
+mg:startFromTitle()
+assert_eq(mg.routine, 0, "Routine must advance to ROUTINE_START_GAME (0) after startFromTitle()")
 assert_eq(mg.hp, 6000, "Initial HP must be 6000 (60.00s)")
 assert_eq(mg.speed, 0.25, "Initial speed must be 0.25")
 assert_eq(mg.distance, 0, "Initial distance must be 0")
-assert_eq(mg.routine, 0, "Initial routine must be ROUTINE_START_GAME (0)")
 assert_eq(mg.pikaState, 0, "Initial Pikachu state must be PIKA_STATE_RIDING (0)")
-print("✓ Initial state test passed")
+print("✓ Initial state & Title transition test passed")
 
 -- Test 2: Start banner transition to RunGame
 for _ = 1, 40 do
@@ -65,6 +67,8 @@ assert_eq(mg.hp, initialHp - 1, "HP should decrease by 1 each frame")
 print("✓ Auto acceleration and HP countdown test passed")
 
 -- Test 4: Landing Evaluation Matrix
+local old_getWaveTile = mg.getWaveTileUnderPika
+mg.getWaveTileUnderPika = function() return 0x01 end -- force open water
 mg.frameSet = 5
 assert_eq(mg:evaluateLanding(), "rough", "Angle 5 on open water should be rough landing")
 mg.frameSet = 6
@@ -77,6 +81,7 @@ for f = 8, 14 do
   mg.frameSet = f
   assert_eq(mg:evaluateLanding(), "wipeout", "Upside-down frame " .. f .. " must be wipeout")
 end
+mg.getWaveTileUnderPika = old_getWaveTile
 print("✓ Landing evaluation matrix test passed (including upside-down frames 8..14)")
 
 -- Test 5: Stunt Scoring
@@ -145,6 +150,128 @@ end
 assert_eq(mg.radness, 0, "Radness should be tallied down to 0")
 assert_eq(mg.totalScore, 300, "Total score should be 300 (100 HP + 200 Radness)")
 assert_eq(mg.routine, 10, "Routine should advance to ROUTINE_WAIT_LAST (10)")
-print("✓ Results tally countdown test passed")
+-- Test 8: Crossing finish line while jumping upside-down crashes into water and rights Pikachu before results
+local mg8 = SurfingMinigame.new(mockGame, nil, true)
+mg8.routine = 1 -- ROUTINE_RUN_GAME
+mg8.distanceFixed = (24 * 128 - 2) * 256
+mg8.speedFixed = 512
+mg8.pikaState = 1 -- PIKA_STATE_JUMPING
+mg8.frameSet = 11 -- Upside down
+mg8.pikaY = 60
+mg8.jumpDescending = true
+mg8.jumpArcMagnitude = 4
+mg8.radness = 150
+local preScore = mg8.radness
+
+-- Update to cross the finish line
+mg8:update()
+assert_eq(mg8.routine, 2, "Routine should advance to ROUTINE_WAIT_RESULTS (2) upon crossing finish")
+assert_eq(mg8.pikaState, 1, "Pikachu should remain mid-air immediately after crossing line")
+
+-- Update until Pikachu lands in water
+while mg8.pikaState == 1 do
+  mg8:update()
+end
+assert_eq(mg8.pikaState, 3, "Upside-down landing post-finish line must trigger PIKA_STATE_CRASHED (3)")
+assert_eq(mg8.radness, preScore, "Radness score must NOT change after crossing finish line")
+assert_eq(mg8.crashTimer, 96, "Crash timer must be initialized to 96 frames")
+
+-- Update while crashed to verify recovery
+while mg8.pikaState == 3 do
+  mg8:update()
+end
+assert_eq(mg8.pikaState, 0, "Pikachu must recover back to PIKA_STATE_RIDING (0) and right itself on the board")
+assert_eq(mg8.frameSet, 4, "Pikachu frameSet must be reset to upright (4)")
+
+-- Let coasting finish and verify transition to results
+while mg8.routine == 2 do
+  mg8:update()
+end
+assert_eq(mg8.routine, 3, "Routine should advance to ROUTINE_SCROLL_RESULTS (3) only after Pikachu is upright")
+print("✓ Mid-air upside-down finish line crossing crash & recovery test passed")
+
+-- Test 9: Crossing finish line while upright jumping lands cleanly and proceeds
+local mg9 = SurfingMinigame.new(mockGame, nil, true)
+mg9.routine = 1
+mg9.distanceFixed = (24 * 128 - 2) * 256
+mg9.speedFixed = 512
+mg9.pikaState = 1
+mg9.frameSet = 4 -- Clean flat
+mg9.pikaY = 60
+mg9.jumpDescending = true
+mg9.jumpArcMagnitude = 4
+mg9.radness = 200
+preScore = mg9.radness
+
+mg9:update()
+assert_eq(mg9.routine, 2, "Routine should advance to ROUTINE_WAIT_RESULTS (2)")
+
+while mg9.pikaState == 1 do
+  mg9:update()
+end
+assert_eq(mg9.pikaState, 2, "Upright landing post-finish line must trigger PIKA_STATE_LANDING (2)")
+assert_eq(mg9.radness, preScore, "Radness score must NOT change post-finish")
+
+while mg9.pikaState == 2 do
+  mg9:update()
+end
+assert_eq(mg9.pikaState, 0, "Pikachu must return to PIKA_STATE_RIDING (0)")
+print("✓ Mid-air upright finish line crossing test passed")
+
+-- Test 10: Crossing finish line while already crashed recovers before results
+local mg10 = SurfingMinigame.new(mockGame, nil, true)
+mg10.routine = 1
+mg10.distanceFixed = (24 * 128 - 2) * 256
+mg10.speedFixed = 512
+mg10.pikaState = 3 -- PIKA_STATE_CRASHED
+mg10.crashTimer = 50
+
+mg10:update()
+assert_eq(mg10.routine, 2, "Routine should advance to ROUTINE_WAIT_RESULTS (2)")
+assert_eq(mg10.pikaState, 3, "Pikachu should still be crashed")
+
+while mg10.pikaState == 3 do
+  mg10:update()
+end
+assert_eq(mg10.pikaState, 0, "Pikachu must recover upright before proceeding to results")
+print("✓ Pre-crashed finish line crossing recovery test passed")
+
+-- Test 11: Decoupled timestep accumulator (60Hz and 144Hz framerate consistency)
+local mg11_60 = SurfingMinigame.new(mockGame, nil, true)
+mg11_60.routine = 1 -- ROUTINE_RUN_GAME
+for _ = 1, 60 do
+  mg11_60:update(1 / 60)
+end
+assert(mg11_60.t == 59 or mg11_60.t == 60, "60Hz update over 1s must produce approx 60 ticks (got " .. mg11_60.t .. ")")
+
+local mg11_144 = SurfingMinigame.new(mockGame, nil, true)
+mg11_144.routine = 1 -- ROUTINE_RUN_GAME
+for _ = 1, 144 do
+  mg11_144:update(1 / 144)
+end
+assert(mg11_144.t == 59 or mg11_144.t == 60, "144Hz update over 1s must produce approx 60 ticks (got " .. mg11_144.t .. ")")
+print("✓ Decoupled 59.7275Hz timestep accumulator test passed")
+
+-- Test 12: Landing continuity on slopes (no position jumps while landing)
+local mg12 = SurfingMinigame.new(mockGame, nil, true)
+mg12.routine = 1
+mg12.pikaState = 2 -- PIKA_STATE_LANDING
+mg12.landingTimer = 20
+mg12.speedFixed = 256
+-- Place on a rising wave pattern
+mg12.cols[5] = { pat = SurfingMinigame.WAVE_PATTERNS[0x06], hl = 110, hr = 100 }
+mg12.distanceFixed = (5 * 16 - 80) * 256
+local startY = mg12.pikaY
+mg12:update()
+assert(mg12.pikaY ~= startY, "pikaY must continuously follow wave surface height while in PIKA_STATE_LANDING")
+print("✓ Landing slope height tracking continuity test passed")
+
+-- Test 13: Fixed speed enforcement (minigames must always run at 1X speed)
+assert(mg12.isFixedSpeed == true, "SurfingMinigame must have isFixedSpeed flag enabled")
+assert(mg12.isMinigame == true, "SurfingMinigame must have isMinigame flag enabled")
+local mockStack = { states = { mg12 } }
+local Game = require("src.core.Game")
+assert(Game.isFixedSpeedInStack(mockStack) == true, "Game.isFixedSpeedInStack must return true for SurfingMinigame")
+print("✓ Minigame fixed speed enforcement test passed")
 
 print("All SurfingMinigame unit tests passed successfully!")