Default Tf Path Lookup

Faster startup when --tf-path is not set

When you don't set --tf-path, Terragrunt picks the binary it wraps by looking for tofu on your PATH and falling back to terraform when it isn't there. Terragrunt used to make that choice by running tofu -version, which meant launching a process at the start of every command, including commands like find and list that never run the binary. That process launch is gone, and a terragrunt --version benchmark runs roughly 1.7x faster as a result.

This changes what happens when tofu is on your PATH but can't run: Terragrunt now selects it and reports the failure rather than silently falling back to terraform. Set --tf-path or TG_TF_PATH to pick the binary yourself.