Bumps to 0.1.4 to publish the fs-core bridge module landed via PR #4.

Also adds the version field to the am-fs-core path dep:
  am-fs-core = { path = "../rust-fs-core", version = "0.1" }

The version field is required for `cargo publish` to accept the
crate — bare path deps are stripped, but cargo still wants the
version requirement that consumers of the published crate will see.
The path entry stays so local builds in DiskJockey's umbrella tree
continue to resolve via the sibling submodule rather than the
registry.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>