Plain POSIX files: remove commit on close (fs.rs)

Staging every write until close broke tempfile, git, and SQLite, which
expect normal files. Actors that need an atomic publish write a temporary
file and rename it; the SDK has write_atomic for that.

cli/src/lib.rs

@@ -7,7 +7,6 @@ pub mod broker;
 pub mod candidate;
 pub mod cargo_actor;
 pub mod console;
-pub mod fs;
 pub mod runtime;
 pub mod supervisor;
 pub mod world;