Implement system state management with TOML serialization

- Introduced `SystemState` struct to manage system state, including stage, target, architecture, and layers.
- Added functions to load and save system state from/to a TOML file.
- Implemented layer management functions: add, set, and remove packages from layers.
- Created initialization function for LBI layout, including directory and symlink creation.
- Added tests for layer management and LBI layout initialization.

Cargo.toml

@@ -14,7 +14,7 @@ clap = { version = "4.6.0", features = ["derive"] }
 flate2 = "1.1.9"
 git2 = "0.20.4"
 indicatif = "0.18.4"
-nix = { version = "0.31.2", features = ["user"] }
+nix = { version = "0.31.3", features = ["user"] }
 rusqlite = "0.39.0"
 semver = "1.0.28"
 serde = { version = "1.0.228", features = ["derive"] }
@@ -36,17 +36,18 @@ minisign = "0.9.1"
 petgraph = "0.8.3"
 fd-lock = "4.0.4"
 reqwest = { version = "0.13.2", default-features = false, features = ["blocking", "native-tls"] }
-filetime = "0.2.27"
-clap_complete = "4.6.0"
+filetime = "0.2.29"
+clap_complete = "4.6.5"
 clap_mangen = "0.3.0"
 sys-mount = { version = "3.1.0", default-features = false }
 time = { version = "0.3.47", features = ["formatting", "parsing"] }
 b2sum-rust = "0.3.0"
 serde_ignored = "0.1.14"
-lz4_flex = "0.13.0"
+lz4_flex = "0.13.1"
 lzma-rust2 = "0.16.2"
 signal-hook = "0.4.4"
 sha1 = "0.11.0"
+pdf-extract = "0.10.0"
 
 [dev-dependencies]
 tempfile = "=3.27.0"