Add clap CLI, logging, and update Nix flake

Introduce a clap‑based command line interface and file logging using
simplelog. Add the corresponding dependencies (clap, log, simplelog) and
a release profile with LTO and stripping. Refactor the Nix flake:
update default.nix metadata, improve devShell, add update script and
metadata, and adjust flake.nix outputs accordingly. Update Cargo.lock
to reflect new crates.

Cargo.toml

@@ -1,6 +1,15 @@
 [package]
-name = "rust-flake-template" # change the default name to your project name
+name = "rust-flake-template"
 version = "0.1.0"
 edition = "2024"
 
+[profile.release]
+codegen-units = 1
+lto = true
+opt-level = 3
+strip = true
+
 [dependencies]
+clap = { version = "4.6.1", features = ["derive"] }
+log = "0.4.33"
+simplelog = "0.12.2"