`build` variable in $service-worker module does not include web worker files

Describe the bug

The build variable in the $service-worker module does not include files within the /build/_app/immutable/workers/ directory. Files from other directories such as /build/_app/immutable/chunks/ and /build/_app/immutable/entry/ are included. This needs to be fixed to cache web worker files.

Reproduction

https://github.com/MoonlightOffice/sveltekit-webworker-cache-issue

Logs

No response

System Info

System:
    OS: Linux 6.6 Debian GNU/Linux 12 (bookworm) 12 (bookworm)
    CPU: (8) arm64 unknown
    Memory: 4.47 GB / 7.75 GB
    Container: Yes
    Shell: 5.2.15 - /bin/bash
  Binaries:
    Node: 22.3.0 - /usr/local/bin/node
    Yarn: 1.22.22 - /usr/local/bin/yarn
    npm: 10.8.1 - /usr/local/bin/npm
  npmPackages:
    @sveltejs/adapter-auto: ^3.0.0 => 3.2.2 
    @sveltejs/adapter-static: ^3.0.2 => 3.0.2 
    @sveltejs/kit: ^2.0.0 => 2.5.18 
    @sveltejs/vite-plugin-svelte: ^3.0.0 => 3.1.1 
    svelte: ^5.0.0-next.1 => 5.0.0-next.174 
    vite: ^5.0.3 => 5.3.3

Severity

serious, but I can work around it

Additional Information

No response

Start with the service-worker module described in the linked documentation and run the provided sveltekit-webworker-cache-issue reproduction. Trace how the build variable is assembled, compare its handling of chunks and entry files with the _app/immutable/workers directory, and verify that web worker files are included for caching.