feat(03-01): create library crate, update main.rs imports, add dev-dependencies

- Create src/lib.rs re-exporting all modules as public
- Update main.rs to use encrypted_archive:: imports instead of local mod declarations
- Add dev-dependencies: tempfile, assert_cmd, hex-literal, predicates

src/lib.rs

@@ -0,0 +1,6 @@
+pub mod archive;
+pub mod cli;
+pub mod compression;
+pub mod crypto;
+pub mod format;
+pub mod key;

src/main.rs

@@ -1,12 +1,6 @@
-mod archive;
-mod cli;
-mod compression;
-mod crypto;
-mod format;
-mod key;
-
 use clap::Parser;
-use cli::{Cli, Commands};
+use encrypted_archive::archive;
+use encrypted_archive::cli::{Cli, Commands};
 
 fn main() -> anyhow::Result<()> {
     let cli = Cli::parse();