refactor: put every filesystem write behind one module

src/cli/mod.rs

@@ -1,9 +1,11 @@
+// build.rs reaches these definitions with include!, so nothing here may refer to
+// the rest of the crate: keep this tree to clap definitions only
 mod ahab;
 mod django;
 mod link;
 mod postgres;
 
-pub use ahab::{Ahab, Commands, reject_unsupported_dry_run};
+pub use ahab::{Ahab, Commands};
 pub use django::Django;
 pub use link::Link;
 pub use postgres::{Format, Postgres};