fix: singing bowls ambient + Next.js 16 async params/cookies

Ambient:
- Replace oscillator drone/melody with singing bowl synthesis
- Each bowl: instant attack + exponential decay (7–12s) = real physical sound
- Two detuned copies per strike for natural shimmer beat
- A-minor pentatonic (A3 C4 D4 E4 G4 A4 C5 E5), weighted toward warm lows
- 30% chance of soft harmonic fifth companion tone per strike
- Random gaps 3–8s between strikes so it breathes naturally
- Two long hall reverb tails (2.4s / 4.8s) for warmth and space
- Graceful 2.5s fade-out on stop

Next.js 16 compatibility (breaking changes from v14→v16):
- Dynamic route params now Promise<{...}> → await params in all handlers
- cookies() now returns Promise → isAdmin() made async, await cookies()
- Files: [...path], memories/[id], media/[id], auth, upload all updated

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/app/api/upload/route.ts

@@ -8,8 +8,9 @@ import { getDb } from '@/lib/db'
 export const runtime = 'nodejs'
 export const maxDuration = 60
 
-function isAdmin() {
-  const token = cookies().get('admin_auth')?.value
+async function isAdmin() {
+  const cookieStore = await cookies()
+  const token = cookieStore.get('admin_auth')?.value
   const expected = createHash('sha256')
     .update(process.env.ADMIN_PASSWORD || 'change-me')
     .digest('hex')
@@ -46,7 +47,7 @@ const FOLDER_TO_TYPE: Record<string, 'photo' | 'video' | 'music'> = {
 }
 
 export async function POST(req: NextRequest) {
-  if (!isAdmin()) {
+  if (!await isAdmin()) {
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
@@ -58,11 +59,9 @@ export async function POST(req: NextRequest) {
     return NextResponse.json({ error: 'Keine Datei' }, { status: 400 })
   }
 
-  // Try to detect type from mime or extension
   let mimeType = file.type?.toLowerCase() || ''
   const ext = path.extname(file.name).toLowerCase()
 
-  // iOS HEIC fallback
   if (!mimeType && (ext === '.heic' || ext === '.heif')) {
     mimeType = 'image/heic'
   }