Upgrade whoami to 2.1 and handle username retrieval errors

[pRizz]

Summary

Upgrade the whoami crate from version 1.5 to 2.1, which introduces a breaking API change where whoami::username() now returns a Result instead of a String. This PR updates the dependency and handles the potential error case gracefully.

Changes

• Upgrade whoami dependency from 1.5 to 2.1 in packages/core/Cargo.toml
• Update Cargo.lock to reflect new whoami 2.1.0 and its transitive dependencies:
  • wasite upgraded from 0.1.0 to 1.0.2
  • wasi pinned to 0.11.1+wasi-snapshot-preview1 in existing dependencies
  • New wasi 0.14.7+wasi-0.2.4 added as a dependency of wasite
• Update default_user() function in packages/core/src/host/schema.rs to handle the Result return type by providing a fallback value of "user" when username retrieval fails

Type of Change

• Dependency upgrade (non-breaking change that updates external crate)
• Bug fix (handles potential errors in username retrieval)

Testing

Describe how you tested your changes:

• Unit tests pass (just test-rust)
• Linting passes (just lint)
• Manual testing performed

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings
• Any dependent changes have been merged and published

Related Issues

N/A

https://claude.ai/code/session_01FjPuTe8aJr25G84ScsaTvn