init: archlens — architecture diagram generator

Hex arch + DDD, tree-sitter parsing, Mermaid/ASCII output.
Supports Rust + Python. 92 tests. CI, diff, --check for staleness detection.

crates/domain/tests/language_tests.rs

@@ -0,0 +1,18 @@
+use archlens_domain::Language;
+
+#[test]
+fn known_languages_are_available() {
+    let rust = Language::Rust;
+    let csharp = Language::CSharp;
+    let python = Language::Python;
+
+    assert_eq!(rust.name(), "Rust");
+    assert_eq!(csharp.name(), "CSharp");
+    assert_eq!(python.name(), "Python");
+}
+
+#[test]
+fn languages_are_comparable() {
+    assert_eq!(Language::Rust, Language::Rust);
+    assert_ne!(Language::Rust, Language::Python);
+}