[Mac] False positive disk space error prevents launching Decentraland

## Description

Users on macOS are reporting that Decentraland fails to launch with a "not enough disk space" error (E1004_DISK_FULL), even though they have sufficient free disk space available. This appears to be a false positive in the disk space validation logic.

## Steps to Reproduce

1. Open the Decentraland launcher on macOS
2. Attempt to launch the Explorer
3. Launcher shows a disk space error and prevents launch

## Expected Behavior

The launcher should correctly detect available disk space and allow launching when sufficient space is available.

## Actual Behavior

The launcher reports insufficient disk space and blocks launch, despite the user having adequate free space.

## Possible Cause

macOS APFS volumes report "available" and "purgeable" space separately. The disk space check may not account for purgeable storage that macOS would free on demand, leading to an undercount of actual available space.

## Related Issues

- #8715 — SQLite flush failure due to disk full (genuine disk full, different from this false positive)
- #8163 — Preferences write failure due to disk full (genuine disk full, Mac Only)
- decentraland/launcher-rust#57 — Original error handling infrastructure for disk space checks

## Screenshots

_Screenshots were shared in the internal Slack thread and should be attached here by the reporter._

## Environment

- **Platform:** macOS
- **Component:** Launcher / pre-launch disk space validation