SkyPilot instance accessible to anyone in the workspace with corrupted user_hash

Summary

A stray % character was accidentally written into ~/.sky/user_hash, producing a malformed user identity. Instances launched under that bad hash were accessible to anyone in the workspace rather than being scoped to the owning user.

To fix:

1. Overwrite ~/.sky/user_hash with the correct UUID
2. sky down the bad-hash instances.
3. Launch a new instance under the corrected user_hash

Expected Behavior

The new instance is owned by and accessible only to the user whose user_hash matches the corrected value.