Summary

Implement fd_filestat_set_size for the native and web Preview1 backends.

Parent tracking issue: #15
Suggested implementation order: 12 / 39

Suggested dependencies

• Support writable virtual files and non-stdio fd_write in WASI Preview1 #21 Support writable virtual files and non-stdio fd_write in WASI Preview1
• Expand fd_fdstat_get and fd_filestat_get metadata to better match WASI Preview1 #22 Expand fd_fdstat_get and fd_filestat_get metadata to better match WASI Preview1

References

• https://github.com/WebAssembly/WASI/blob/wasi-0.1/preview1/docs.md#L1652

Acceptance criteria

• fd_filestat_set_size can resize supported virtual files on native and web.
• Tests cover truncation, extension, and invalid descriptor cases.