build(demo): add @zenfs/dom for IndexedDB-backed localstore

Brings in @zenfs/dom@1.2.9 which exposes the IndexedDB backend for ZenFS.
Used to mount /home/user/.bee/mainnet/localstore on IndexedDB so retrieved
chunks survive page reloads (without persisting peer/identity state).

Author: v1rtl

wasm-demo/bun.lock

@@ -9,7 +9,8 @@
     "typescript": "^5"
   },
   "dependencies": {
-    "@zenfs/core": "^2.4.4"
+    "@zenfs/core": "^2.4.4",
+    "@zenfs/dom": "^1.2.9"
   },
   "scripts": {
     "build": "bunx esbuild sw.js --bundle --platform=browser > sw_bundle.js"