feat: add bread-sync module for snapshot and restore functionality

- Introduced `bread-sync` module with core functionalities for syncing system state via Git.
- Implemented `MachineProfile` struct for managing machine profiles, including methods for reading and writing profiles.
- Added package management support with snapshot capabilities for `pacman`, `pip`, `npm`, and `cargo`.
- Created comprehensive tests for sync operations, package parsing, and machine profile management.
- Enhanced `udev` adapter to include vendor and product IDs for scanned devices.
- Updated state engine to handle module clearing commands.
- Introduced Lua integration for accessing machine information and file system operations.
- Improved packaging documentation for Arch Linux and systemd service setup.

bread-cli/tests/modules.rs

@@ -0,0 +1,133 @@
+use bread_cli::modules_mgmt;
+use std::fs;
+use tempfile::TempDir;
+
+/// Helper: create a minimal valid module directory in `dir` with given name.
+fn make_module_dir(dir: &std::path::Path, name: &str, version: &str) -> std::path::PathBuf {
+    let module_dir = dir.join(name);
+    fs::create_dir_all(&module_dir).unwrap();
+    let manifest = format!(
+        r#"name = "{name}"
+version = "{version}"
+description = "Test module"
+author = "test"
+source = "/tmp/test"
+installed_at = ""
+"#
+    );
+    fs::write(module_dir.join("bread.module.toml"), manifest).unwrap();
+    fs::write(module_dir.join("init.lua"), "-- test\n").unwrap();
+    module_dir
+}
+
+#[test]
+fn install_from_local_succeeds_with_manifest() {
+    let src_tmp = TempDir::new().unwrap();
+    let modules_tmp = TempDir::new().unwrap();
+
+    make_module_dir(src_tmp.path(), "mymod", "1.2.3");
+    let src = src_tmp.path().join("mymod");
+
+    let result =
+        modules_mgmt::install_from_local(&src, "test:mymod", modules_tmp.path());
+
+    assert!(result.is_ok(), "install failed: {:?}", result.err());
+    let manifest = result.unwrap();
+    assert_eq!(manifest.name, "mymod");
+    assert_eq!(manifest.version, "1.2.3");
+
+    // Module directory must exist in modules dir
+    assert!(modules_tmp.path().join("mymod").exists());
+    assert!(modules_tmp.path().join("mymod").join("bread.module.toml").exists());
+    assert!(modules_tmp.path().join("mymod").join("init.lua").exists());
+}
+
+#[test]
+fn install_from_local_fails_without_manifest() {
+    let src_tmp = TempDir::new().unwrap();
+    let modules_tmp = TempDir::new().unwrap();
+
+    // No bread.module.toml in src
+    let src = src_tmp.path();
+    fs::write(src.join("init.lua"), "-- no manifest\n").unwrap();
+
+    let result = modules_mgmt::install_from_local(src, "test:nomod", modules_tmp.path());
+    assert!(result.is_err());
+    let msg = result.unwrap_err().to_string();
+    assert!(
+        msg.contains("bread.module.toml"),
+        "expected error about bread.module.toml, got: {msg}"
+    );
+}
+
+#[test]
+fn remove_deletes_module_directory() {
+    let modules_tmp = TempDir::new().unwrap();
+    make_module_dir(modules_tmp.path(), "delme", "0.1.0");
+
+    // Verify it exists before removal
+    assert!(modules_tmp.path().join("delme").exists());
+
+    let result = modules_mgmt::remove_module("delme", modules_tmp.path());
+    assert!(result.is_ok(), "remove failed: {:?}", result.err());
+    assert!(!modules_tmp.path().join("delme").exists());
+}
+
+#[test]
+fn remove_nonexistent_errors() {
+    let modules_tmp = TempDir::new().unwrap();
+    let result = modules_mgmt::remove_module("ghost", modules_tmp.path());
+    assert!(result.is_err());
+    let msg = result.unwrap_err().to_string();
+    assert!(msg.contains("ghost"), "expected error mentioning module name, got: {msg}");
+}
+
+#[test]
+fn list_reads_manifests_from_disk() {
+    let modules_tmp = TempDir::new().unwrap();
+    make_module_dir(modules_tmp.path(), "alpha", "1.0.0");
+    make_module_dir(modules_tmp.path(), "beta", "2.0.0");
+
+    // Add a non-module dir (no manifest) — should be ignored
+    fs::create_dir_all(modules_tmp.path().join("notamodule")).unwrap();
+
+    let modules = modules_mgmt::list_modules(modules_tmp.path()).unwrap();
+    assert_eq!(modules.len(), 2);
+    assert_eq!(modules[0].name, "alpha");
+    assert_eq!(modules[1].name, "beta");
+}
+
+#[test]
+fn manifest_written_correctly_on_install() {
+    let src_tmp = TempDir::new().unwrap();
+    let modules_tmp = TempDir::new().unwrap();
+
+    make_module_dir(src_tmp.path(), "installtest", "3.0.0");
+    let src = src_tmp.path().join("installtest");
+
+    let manifest =
+        modules_mgmt::install_from_local(&src, "github:test/installtest", modules_tmp.path())
+            .unwrap();
+
+    // All required fields must be present and non-empty
+    assert_eq!(manifest.name, "installtest");
+    assert_eq!(manifest.version, "3.0.0");
+    assert!(!manifest.description.is_empty());
+    assert!(!manifest.author.is_empty());
+    assert_eq!(manifest.source, "github:test/installtest");
+    assert!(!manifest.installed_at.is_empty());
+
+    // installed_at must be valid RFC 3339
+    let parsed = chrono::DateTime::parse_from_rfc3339(&manifest.installed_at);
+    assert!(
+        parsed.is_ok(),
+        "installed_at '{}' is not valid RFC 3339",
+        manifest.installed_at
+    );
+
+    // Verify the on-disk manifest also has all fields
+    let on_disk = modules_mgmt::read_module_manifest("installtest", modules_tmp.path()).unwrap();
+    assert_eq!(on_disk.name, manifest.name);
+    assert_eq!(on_disk.installed_at, manifest.installed_at);
+    assert_eq!(on_disk.source, "github:test/installtest");
+}