animation: unify lightning and thunderstorm components

Replace the old Lightning bolt renderer with the Thunderstorm component,
which now supports both strike mode (single bolt for zaps) and full storm
mode (clouds, fog, multiple bolts for wallet send success).

- Add strike intensity that fires a single bolt without clouds/fog/flash
- Convert StormBolt to ES class with configurable presets (BOLT_STORM vs
  BOLT_STRIKE) matching original visual behavior of each
- Delta-time all animation: bolt growth, fade, flash, cloud drift, and
  strike chance are now frame-rate independent
- Use Path2D for bolt segments instead of replaying all draw calls
- Add ThunderstormProvider/useThunderstrike hook (replaces class-based
  LightningProvider)
- useAnimationEnabled defaults to off when prefers-reduced-motion is
  active; useAnimation respects the same default
- Reduced-motion users get immediate dismiss for all intensities
- Recursive isTreeDone check prevents grandchild bolts from vanishing
  mid-fade
- Stabilize onDone via ref to prevent spurious re-fires
- Delete components/animation/lightning.js

Author: huumn

components/animation/index.js

@@ -2,42 +2,37 @@ import { useCallback, useEffect, useState } from 'react'
 import { useMe } from '@/components/me'
 import { randInRange } from '@/lib/rand'
 
-import { LightningProvider, useLightning } from './lightning'
-// import { SnowProvider, useSnow } from './snow'
-
-const [SelectedAnimationProvider, useSelectedAnimation] = [
-  LightningProvider, useLightning
-  // SnowProvider, useSnow // TODO: the snow animation doesn't seem to work anymore
-]
+import { ThunderstormProvider, useThunderstrike } from '@/components/thunderstorm/provider'
 
 export function AnimationProvider ({ children }) {
   return (
-    <SelectedAnimationProvider>
+    <ThunderstormProvider>
       <AnimationHooks>
         {children}
       </AnimationHooks>
-    </SelectedAnimationProvider>
+    </ThunderstormProvider>
   )
 }
 
 export function useAnimation () {
-  const animate = useSelectedAnimation()
+  const strike = useThunderstrike()
 
   return useCallback(() => {
-    const should = window.localStorage.getItem('lnAnimate') || 'yes'
-    if (should !== 'yes') return false
-    animate()
+    if (!getAnimationDefault()) return false
+    strike()
     return true
-  }, [animate])
+  }, [strike])
 }
 
-export function useAnimationEnabled () {
-  const [enabled, setEnabled] = useState(undefined)
+function getAnimationDefault () {
+  if (typeof window === 'undefined') return undefined
+  const stored = window.localStorage.getItem('lnAnimate')
+  if (stored) return stored === 'yes'
+  return !window.matchMedia('(prefers-reduced-motion: reduce)').matches
+}
 
-  useEffect(() => {
-    const enabled = window.localStorage.getItem('lnAnimate') || 'yes'
-    setEnabled(enabled === 'yes')
-  }, [])
+export function useAnimationEnabled () {
+  const [enabled, setEnabled] = useState(getAnimationDefault)
 
   const toggleEnabled = useCallback(() => {
     setEnabled(enabled => {