feat: add CLI commands and server default behavior

- Introduced CLI commands for server, login, upload, sign, verify, and more using `clap`.
- Updated Dockerfile and docker-compose to default to `server` command on startup.
- Enhanced `test_local.sh` for testing the server and client operations.
- Added multipart support to `reqwest` and new CLI documentation in `README.md`.
- Updated `Cargo.toml` with new dependencies to support CLI and multipart uploads.

Dockerfile

@@ -31,5 +31,7 @@ RUN apt-get update && apt-get install -y vault
 WORKDIR /usr/local/bin
 
 COPY --from=builder /usr/src/vault-hier/target/release/vault-hier .
-# Set the entrypoint to directly run the Rust binary
+
+# Set the entrypoint to directly run the Rust binary with the server command by default
 ENTRYPOINT ["/usr/local/bin/vault-hier"]
+CMD ["server"]