Create fe.toml and basic definition for fe project.

We will push fe project config to fe.toml? The idea is config something e.g ignot, package manager or fe version manager. fe.toml also help `fe` bin found and recognize fe project more easier.

The issue names a new fe.toml file and the `fe` binary, but no existing files or tests are identified. First clarify which project settings belong in the file and how project recognition should work; done should include agreed behavior for configuration, package-manager or version-manager settings, and `fe` project detection.

Written by the indexing model from the issue text.