refactor: move scattered business logic into domain

- CodeGraph::merge_project_edges() replaces presentation-layer function
- Language::is_test_file() centralises test file detection (was in walkdir)
- AnalysisConfig::is_standard_excluded() centralises default dir exclusions (was in walkdir)
- normalize_cargo_package() / normalize_python_package() in domain replace duplicated normalisers in each adapter
- walkdir, cargo-workspace, python-project updated to call domain methods

crates/adapters/walkdir/src/walkdir_discovery.rs

@@ -6,20 +6,6 @@ use archlens_domain::{
     AnalysisConfig, DomainError, FilePath, Language, SourceFile, ports::FileDiscovery,
 };
 
-const DEFAULT_EXCLUDES: &[&str] = &[
-    ".venv",
-    "venv",
-    "node_modules",
-    "__pycache__",
-    ".git",
-    "target",
-    "bin",
-    "obj",
-    "dist",
-    ".tox",
-    ".eggs",
-];
-
 pub struct WalkdirDiscovery;
 
 impl Default for WalkdirDiscovery {
@@ -42,34 +28,13 @@ impl WalkdirDiscovery {
         }
     }
 
-    fn is_test_file(path: &Path, language: Language) -> bool {
-        let stem = path
-            .file_stem()
-            .and_then(|s| s.to_str())
-            .unwrap_or_default();
-        let in_tests_dir = path
-            .parent()
-            .map(|p| p.components().any(|c| c.as_os_str() == "tests"))
-            .unwrap_or(false);
-
-        if in_tests_dir {
-            return true;
-        }
-
-        match language {
-            Language::Rust => stem.ends_with("_test") || stem.ends_with("_tests"),
-            Language::Python => stem.starts_with("test_") || stem.ends_with("_test"),
-            Language::CSharp => stem.ends_with("Tests") || stem.ends_with("Test"),
-        }
-    }
-
     fn is_excluded(path: &Path, root: &Path, excludes: &[String]) -> bool {
         let relative = path.strip_prefix(root).unwrap_or(path);
         let relative_str = relative.to_string_lossy();
 
         for component in relative.components() {
             let name = component.as_os_str().to_string_lossy();
-            if DEFAULT_EXCLUDES.iter().any(|e| name == *e) {
+            if AnalysisConfig::is_standard_excluded(&name) {
                 return true;
             }
         }
@@ -109,7 +74,7 @@ impl FileDiscovery for WalkdirDiscovery {
             }
 
             if let Some(language) = Self::detect_language(path) {
-                if !config.include_tests() && Self::is_test_file(path, language) {
+                if !config.include_tests() && language.is_test_file(path) {
                     continue;
                 }
                 if let Some(changed) = config.changed_files() {