fix(p10-1b): apply round-1 lang.rs doc + tests/ test case missed in 4503b5b

PR #142 round-1 fix commit 4503b5b 보고에는 lang.rs 의 (a) module_path_for_python
doc comment 갱신 (tests/examples/benches 가 의도적으로 strip 안 됨 명시) 과
(b) tests/test_foo.py → tests.test_foo 단언 추가가 포함됐다고 적혔으나,
실제 commit 에는 lang.rs 변경이 staging 되지 않아 main 에 안 들어감 (review
loop round 2 이 working tree 상태만 신뢰하고 commit 검증을 안 함).

이번 PR 이 누락된 (5)+(6) 항목만 retro 적용. lang.rs +9 lines (test 1 +
doc 4 + 주석 2 + 빈줄 2). cargo test -p kebab-parse-code --lib → 20/20 pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-parse-code/src/lang.rs

@@ -44,6 +44,12 @@ pub fn code_lang_for_path(path: &Path) -> Option<&'static str> {
 /// p10-1B: workspace-relative Python file path → dotted module-path prefix.
 /// See plan §Task C for the exact rules + tasks/p10/p10-1b for the §3.4
 /// design contract.
+///
+/// Stripped source-roots: `src/`, `lib/`, and `crates/<crate>/src/`.
+/// `tests/`, `examples/`, and `benches/` are intentionally NOT stripped —
+/// they appear in test/example/bench namespaces and dropping them would
+/// conflate identical symbol names across conventional Python directories
+/// (e.g. `tests/test_foo.py` → `tests.test_foo`, not `test_foo`).
 pub fn module_path_for_python(workspace_path: &str) -> String {
     let mut p: &str = workspace_path;
     if let Some(rest) = p.strip_prefix("crates/") {
@@ -97,6 +103,9 @@ mod tests {
         assert_eq!(module_path_for_python("a/b/c.pyi"),                   "a.b.c");
         assert_eq!(module_path_for_python("standalone.py"),               "standalone");
         assert_eq!(module_path_for_python("src/__init__.py"),             "");
+        // `tests/` is NOT a stripped source-root — it is preserved as
+        // part of the module path so test symbols stay namespaced.
+        assert_eq!(module_path_for_python("tests/test_foo.py"),           "tests.test_foo");
     }
 
     #[test]