fix unused variable errors for production build

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/features/song-select/SongCard.tsx

@@ -1,5 +1,4 @@
 import { playSound, SFX_BUTTON_DEFAULT } from '../../lib/sounds'
-import { lighten } from './color-utils'
 import type { Song } from './types'
 
 type SongCardProps = {
@@ -10,7 +9,7 @@ type SongCardProps = {
   onClick: () => void
 }
 
-function renderDifficultyDots(difficulty: number, color: string, active: boolean) {
+function renderDifficultyDots(difficulty: number) {
   return (
     <div className="song-card__difficulty" aria-label={`Difficulty ${difficulty} out of 5`}>
       {Array.from({ length: 5 }).map((_, index) => {
@@ -67,7 +66,7 @@ export function SongCard({ song, trackNumber, offset, isActive, onClick }: SongC
       <p className="song-card__artist">{song.artist}</p>
       <div className="song-card__bottom-row">
         <p className="song-card__bpm">{song.bpm} BPM</p>
-        {renderDifficultyDots(song.difficulty, song.color, isActive)}
+        {renderDifficultyDots(song.difficulty)}
       </div>
     </button>
   )

src/features/song-select/SongInfoBar.tsx

@@ -10,7 +10,7 @@ type SongInfoBarProps = {
   onConfirm: () => void
 }
 
-function DifficultyDots({ difficulty, color }: { difficulty: number; color: string }) {
+function DifficultyDots({ difficulty }: { difficulty: number }) {
   return (
     <div className="song-info-bar__dots" aria-label={`Difficulty ${difficulty} out of 5`}>
       {Array.from({ length: 5 }).map((_, index) => (
@@ -75,7 +75,7 @@ export function SongInfoBar({ song, onConfirm }: SongInfoBarProps) {
         </div>
 
         <div className="song-info-bar__stat">
-          <DifficultyDots difficulty={song.difficulty} color={song.color} />
+          <DifficultyDots difficulty={song.difficulty} />
           <span className="song-info-bar__label font-caption">DIFF</span>
         </div>
 

src/game/ArrowGame.tsx

@@ -19,10 +19,6 @@ const PERFECT_WINDOW = 180
 const GOOD_WINDOW = 350
 const CLEANUP_DELAY = 600
 
-// Random mode fallback
-const RANDOM_SPAWN_INTERVAL = 1800
-const RANDOM_DIRECTIONS: ArrowDirection[] = ['left', 'up', 'down', 'right']
-
 const STEP_TO_ARROW: Record<StepDirection, ArrowDirection> = {
   left: 'left',
   right: 'right',
@@ -54,7 +50,7 @@ export const ArrowGame = forwardRef<ArrowGameHandle, Props>(({ active = true, ch
   const arrowsRef = useRef<GameArrow[]>([])
   const nextId = useRef(0)
   const [arrows, setArrows] = useState<GameArrow[]>([])
-  const [score, setScore] = useState({ perfect: 0, good: 0, miss: 0, combo: 0 })
+  const [, setScore] = useState({ perfect: 0, good: 0, miss: 0, combo: 0 })
   const comboRef = useRef(0)
   const [judgment, setJudgment] = useState<{ text: string; key: number; x: number; y: number; rot: number } | null>(null)
   const judgmentTimer = useRef<ReturnType<typeof setTimeout> | null>(null)

src/pages/GamePage.tsx

@@ -2,7 +2,6 @@ import { useCallback, useEffect, useRef, useState } from 'react'
 import { Navigate, useNavigate } from 'react-router-dom'
 import { ROUTE_PATHS } from '../app/route-paths'
 import { playSound, SFX_BUTTON_DEFAULT } from '../lib/sounds'
-import { SONGS } from '../features/song-select/song-data'
 import { useGameStatsStore } from '../stores/game-stats/store'
 import { ArrowGame } from '../game/ArrowGame'
 import type { ArrowGameHandle } from '../game/ArrowGame'
@@ -107,7 +106,6 @@ export function GamePage() {
 
   // Score delta floater + combo
   const [scoreDelta, setScoreDelta] = useState<{ value: number; key: number; dx: number; dy: number } | null>(null)
-  const [scorePulse, setScorePulse] = useState(0)
   const [combo, setCombo] = useState(0)
 
   // Scoring: base points + combo bonus (capped at 4x)
@@ -134,7 +132,6 @@ export function GamePage() {
           dx: 20 + Math.random() * 80,
           dy: -10 + Math.random() * 40,
         })
-        setScorePulse(Date.now())
       }
     },
     [addPerfectHit, addGoodHit, addMiss, addScore],