`unknown` should be used instead of `any` for `getItems`

Describe the bug

I noticed that in this snippet, value's type is any
https://github.com/wxt-dev/wxt/blob/d2702506332c03f40bfda9b3b59e4c4928e3099b/packages/wxt/src/storage.ts#L481-L485

I'm pretty sure the type should rather be unknown | null

Steps to reproduce

No response

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (20) x64 Intel(R) Core(TM) i7-6950X CPU @ 3.00GHz
    Memory: 37.10 GB / 63.91 GB
  Binaries:
    Node: 20.14.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.7.0 - C:\Program Files\nodejs\npm.CMD
    pnpm: 9.11.0 - C:\Program Files\nodejs\pnpm.CMD
  Browsers:
    Edge: Chromium (127.0.2651.74)
    Internet Explorer: 11.0.19041.4355
  npmPackages:
    wxt: ^0.19.10 => 0.19.10

Used Package Manager

pnpm

Validations

• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Open packages/wxt/src/storage.ts at lines 481-485 and inspect the getItems type declaration. Check the surrounding storage API and run the repository's existing type checks or tests. Done means getItems no longer exposes any and its public value type matches the issue's requested unknown | null.