feat: implement all P1/P2/P3/P4 improvements from issue backlog

P1 correctness:
- filter test files by default (--include-tests to opt in)
- per-module diagrams show cross-module dependency arrows
- qualified type names (Module::TypeName) fix false edges from duplicate names

P2 output richness:
- method parameter types and return types in class diagrams (Rust + Python)
- Python pyproject.toml project analyzer (--level project for monorepos)

P3 unique value:
- boundary rules in archlens.toml ([rules] allow/deny, --strict enforcement)

P4 nice to have:
- dependency weight labels on module arrows (--no-weights to disable)
- --watch mode with 500ms debounce
- D2 renderer adapter (--format d2)
- interactive self-contained HTML viewer (--format html)
- git-aware incremental analysis (--since <ref>)

crates/adapters/d2/tests/d2_renderer_tests.rs

@@ -0,0 +1,110 @@
+use archlens_d2::D2Renderer;
+use archlens_domain::{
+    CodeElement, CodeElementKind, CodeGraph, DiagramLevel, FilePath, ModuleName, Relationship,
+    RelationshipKind, ports::DiagramRenderer,
+};
+
+fn make_el(name: &str, module: Option<&str>) -> CodeElement {
+    let mut el = CodeElement::new(
+        name,
+        CodeElementKind::Class,
+        FilePath::new(&format!("src/{name}.rs")).unwrap(),
+        1,
+    )
+    .unwrap();
+    if let Some(m) = module {
+        el = el.with_module(ModuleName::new(m).unwrap());
+    }
+    el
+}
+
+#[test]
+fn type_level_emits_class_shapes() {
+    let mut graph = CodeGraph::new();
+    graph.add_element(make_el("OrderService", Some("App")));
+    graph.add_element(make_el("Order", Some("Domain")));
+    graph.add_relationship(
+        Relationship::new("OrderService", "Order", RelationshipKind::Composition).unwrap(),
+    );
+    let graph = graph.qualify();
+
+    let renderer = D2Renderer::new();
+    let output = renderer.render(&graph).unwrap();
+    let content = output.files()[0].content();
+
+    assert!(
+        content.contains("shape: class"),
+        "expected class shape: {content}"
+    );
+    assert!(
+        content.contains("OrderService"),
+        "expected OrderService: {content}"
+    );
+    assert!(content.contains("Order"), "expected Order: {content}");
+}
+
+#[test]
+fn module_level_emits_module_nodes_and_edges() {
+    let mut graph = CodeGraph::new();
+    graph.add_element(make_el("Service", Some("App")));
+    graph.add_element(make_el("Order", Some("Domain")));
+    graph.add_relationship(
+        Relationship::new("Service", "Order", RelationshipKind::Composition).unwrap(),
+    );
+    let graph = graph.qualify();
+
+    let renderer = D2Renderer::with_level(DiagramLevel::Module);
+    let output = renderer.render(&graph).unwrap();
+    let content = output.files()[0].content();
+
+    assert!(content.contains("App"), "expected App module: {content}");
+    assert!(
+        content.contains("Domain"),
+        "expected Domain module: {content}"
+    );
+    assert!(
+        content.contains("->"),
+        "expected dependency arrow: {content}"
+    );
+}
+
+#[test]
+fn project_level_groups_by_module() {
+    let mut graph = CodeGraph::new();
+    graph.add_element(
+        CodeElement::new(
+            "my-api",
+            CodeElementKind::Project,
+            FilePath::new("api/pyproject.toml").unwrap(),
+            1,
+        )
+        .unwrap()
+        .with_module(ModuleName::new("Backend").unwrap()),
+    );
+    graph.add_element(
+        CodeElement::new(
+            "my-commons",
+            CodeElementKind::Project,
+            FilePath::new("commons/pyproject.toml").unwrap(),
+            1,
+        )
+        .unwrap(),
+    );
+    graph.add_relationship(
+        Relationship::new("my-api", "my-commons", RelationshipKind::Composition).unwrap(),
+    );
+
+    let renderer = D2Renderer::with_level(DiagramLevel::Project);
+    let output = renderer.render(&graph).unwrap();
+    let content = output.files()[0].content();
+
+    assert!(
+        content.contains("Backend"),
+        "expected Backend group: {content}"
+    );
+    assert!(
+        content.contains("my-api") || content.contains("my_api"),
+        "expected my-api: {content}"
+    );
+    assert!(content.contains("->"), "expected dep arrow: {content}");
+}