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/rhai_tests.rs

@@ -0,0 +1,52 @@
+use sal_git::rhai::*;
+use rhai::Engine;
+
+#[test]
+fn test_register_git_module() {
+    let mut engine = Engine::new();
+    let result = register_git_module(&mut engine);
+    assert!(result.is_ok());
+}
+
+#[test]
+fn test_git_tree_new_function_registered() {
+    let mut engine = Engine::new();
+    register_git_module(&mut engine).unwrap();
+    
+    // Test that the function is registered by trying to call it
+    // This will fail because /nonexistent doesn't exist, but it proves the function is registered
+    let result = engine.eval::<String>(r#"
+        let result = "";
+        try {
+            let git_tree = git_tree_new("/nonexistent");
+            result = "success";
+        } catch(e) {
+            result = "error_caught";
+        }
+        result
+    "#);
+    
+    assert!(result.is_ok());
+    assert_eq!(result.unwrap(), "error_caught");
+}
+
+#[test]
+fn test_git_clone_function_registered() {
+    let mut engine = Engine::new();
+    register_git_module(&mut engine).unwrap();
+    
+    // Test that git_clone function is registered and returns an error as expected
+    let result = engine.eval::<String>(r#"
+        let result = "";
+        try {
+            git_clone("https://example.com/repo.git");
+            result = "unexpected_success";
+        } catch(e) {
+            result = "error_caught";
+        }
+        result
+    "#);
+    
+    assert!(result.is_ok());
+    assert_eq!(result.unwrap(), "error_caught");
+}