feat: Convert SAL to a Rust monorepo

- Migrate SAL project from single-crate to monorepo structure
- Create independent packages for individual modules
- Improve build efficiency and testing capabilities
- Update documentation to reflect new structure
- Successfully convert the git module to an independent package.

git/tests/git_executor_tests.rs

@@ -0,0 +1,139 @@
+use sal_git::*;
+use std::collections::HashMap;
+
+#[test]
+fn test_git_executor_new() {
+    let executor = GitExecutor::new();
+    // We can't directly access the config field since it's private,
+    // but we can test that the executor was created successfully
+    let _executor = executor;
+}
+
+#[test]
+fn test_git_executor_default() {
+    let executor = GitExecutor::default();
+    let _executor = executor;
+}
+
+#[test]
+fn test_git_config_status_serialization() {
+    let status_ok = GitConfigStatus::Ok;
+    let status_error = GitConfigStatus::Error;
+
+    let json_ok = serde_json::to_string(&status_ok).unwrap();
+    let json_error = serde_json::to_string(&status_error).unwrap();
+
+    assert_eq!(json_ok, "\"ok\"");
+    assert_eq!(json_error, "\"error\"");
+}
+
+#[test]
+fn test_git_config_status_deserialization() {
+    let status_ok: GitConfigStatus = serde_json::from_str("\"ok\"").unwrap();
+    let status_error: GitConfigStatus = serde_json::from_str("\"error\"").unwrap();
+
+    assert_eq!(status_ok, GitConfigStatus::Ok);
+    assert_eq!(status_error, GitConfigStatus::Error);
+}
+
+#[test]
+fn test_git_server_auth_serialization() {
+    let auth = GitServerAuth {
+        sshagent: Some(true),
+        key: None,
+        username: None,
+        password: None,
+    };
+
+    let json = serde_json::to_string(&auth).unwrap();
+    assert!(json.contains("\"sshagent\":true"));
+}
+
+#[test]
+fn test_git_server_auth_deserialization() {
+    let json = r#"{"sshagent":true,"key":null,"username":null,"password":null}"#;
+    let auth: GitServerAuth = serde_json::from_str(json).unwrap();
+
+    assert_eq!(auth.sshagent, Some(true));
+    assert_eq!(auth.key, None);
+    assert_eq!(auth.username, None);
+    assert_eq!(auth.password, None);
+}
+
+#[test]
+fn test_git_config_serialization() {
+    let mut auth_map = HashMap::new();
+    auth_map.insert(
+        "github.com".to_string(),
+        GitServerAuth {
+            sshagent: Some(true),
+            key: None,
+            username: None,
+            password: None,
+        },
+    );
+
+    let config = GitConfig {
+        status: GitConfigStatus::Ok,
+        auth: auth_map,
+    };
+
+    let json = serde_json::to_string(&config).unwrap();
+    assert!(json.contains("\"status\":\"ok\""));
+    assert!(json.contains("\"github.com\""));
+}
+
+#[test]
+fn test_git_config_deserialization() {
+    let json = r#"{"status":"ok","auth":{"github.com":{"sshagent":true,"key":null,"username":null,"password":null}}}"#;
+    let config: GitConfig = serde_json::from_str(json).unwrap();
+
+    assert_eq!(config.status, GitConfigStatus::Ok);
+    assert!(config.auth.contains_key("github.com"));
+    assert_eq!(config.auth["github.com"].sshagent, Some(true));
+}
+
+#[test]
+fn test_git_executor_error_display() {
+    let error = GitExecutorError::GitCommandFailed("command failed".to_string());
+    assert_eq!(format!("{}", error), "Git command failed: command failed");
+
+    let error = GitExecutorError::SshAgentNotLoaded;
+    assert_eq!(format!("{}", error), "SSH agent is not loaded");
+
+    let error = GitExecutorError::AuthenticationError("auth failed".to_string());
+    assert_eq!(format!("{}", error), "Authentication error: auth failed");
+}
+
+#[test]
+fn test_git_executor_error_from_redis_error() {
+    let redis_error = redis::RedisError::from((redis::ErrorKind::TypeError, "type error"));
+    let git_error = GitExecutorError::from(redis_error);
+
+    match git_error {
+        GitExecutorError::RedisError(_) => {}
+        _ => panic!("Expected RedisError variant"),
+    }
+}
+
+#[test]
+fn test_git_executor_error_from_serde_error() {
+    let serde_error = serde_json::from_str::<GitConfig>("invalid json").unwrap_err();
+    let git_error = GitExecutorError::from(serde_error);
+
+    match git_error {
+        GitExecutorError::JsonError(_) => {}
+        _ => panic!("Expected JsonError variant"),
+    }
+}
+
+#[test]
+fn test_git_executor_error_from_io_error() {
+    let io_error = std::io::Error::new(std::io::ErrorKind::NotFound, "file not found");
+    let git_error = GitExecutorError::from(io_error);
+
+    match git_error {
+        GitExecutorError::CommandExecutionError(_) => {}
+        _ => panic!("Expected CommandExecutionError variant"),
+    }
+}