Fix pre-commit rustfmt skip paths for core crate

[Shiven0504]

Summary

This PR updates the pre-commit hook to reflect the repository's current crate layout for rustfmt skip checks.

Previously, the hook excluded messages.rs and crates/spacetimedb-core/src/protobuf/*.rs. Since the repository no longer contains the protobuf directory under spacetimedb-core, the skip pattern had become outdated, causing messages.rs to be formatted instead of being excluded.

This change updates the skip paths so the hook correctly matches the current repository structure. Fixes #5532

API and ABI Breaking Changes

• None.

Risk / Complexity

• Complexity: 1 (Trivial)
• Risk: Low. This is a maintenance-only change affecting git hook path matching and has no impact on runtime behavior.

Testing

• Verified the updated hook diff.

• Confirmed the skip paths match the current repository layout.

• Validated the hook syntax using:

  bash -n git-hooks/hooks/pre-commit