Move module definitions after imports

The style guide says: "Put imports before module declarations."
See https://doc.rust-lang.org/style-guide/items.html

Cargo also does this automatically.

gdn-cli/src/commands.rs

@@ -1,9 +1,9 @@
-mod migrate;
-
 use clap::Parser;
 
 use crate::Environment;
 
+mod migrate;
+
 #[derive(Debug, Parser)]
 pub enum Command {
     Migrate(migrate::Command),

gdn-cli/src/main.rs

@@ -1,11 +1,11 @@
-mod commands;
-
 use std::path::PathBuf;
 
 use clap::Parser;
 
 use crate::commands::Command;
 
+mod commands;
+
 /// GedächtNAS - external storage for your brain.
 #[derive(Debug, Parser)]
 #[command(version)]