fix(checker): anchor the test attribute — #[cfg(test)] contains 'test'

Seventh silent success, found by CC-command on PR #41, and the THIRD instance
in this campaign of one class: matching a substring where an exact token was
meant.

'test' in s also matched '#[cfg(test)]', so every cfg-gated fixture was accepted
as a test by --check-evidence — a gate written to reject exactly those. Two
plain fixtures cleared it: Host::model and Sessions::apply_caught_up.

The first instance was the bd dead-ID audit's unanchored exclusion list, where
a real ticket improvise-gp12 would have been silently excluded because it
starts with a crate name. The second was --check-evidence accepting any fn.
This is the third.

Now matched by exact attribute path (test, tokio::test, async_std::test,
wasm_bindgen_test). Fault-injected: a #[cfg(test)] fn under a ### heading is
reported as an orphan, a #[test] fn is not. Re-ran over the five merged units:
215 entries still pass, so none of them relied on the hole.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/check-comment-runs.py

@@ -87,6 +87,23 @@ def rust_files(roots):
                     yield os.path.join(dirpath, f)
 
 
+_TEST_ATTRS = ("test", "tokio::test", "async_std::test", "wasm_bindgen_test")
+
+
+def _is_test_attribute(line):
+    """True only for an attribute that actually marks a test.
+
+    Matched by exact path, never by substring: `#[cfg(test)]` contains "test"
+    and marks a compilation condition, not a test.
+    """
+    body = line.strip()
+    if not body.startswith("#["):
+        return False
+    body = body[2:].rstrip()
+    body = body[:-1] if body.endswith("]") else body
+    return body.strip().strip(":") in _TEST_ATTRS
+
+
 EVIDENCE_DIR = os.path.join("context", "test-evidence")
 
 
@@ -136,7 +153,11 @@ def check_evidence(roots):
                 if proptest_depth <= 0:
                     proptest_depth = None if "{" in raw else 0
             in_proptest = proptest_depth is not None
-            if s.startswith("#[") and ("test" in s or "tokio::test" in s):
+            # ANCHOR the attribute. `"test" in s` also matched `#[cfg(test)]`,
+            # so every cfg-gated fixture cleared a gate written to reject
+            # exactly those -- the third instance of the unanchored-substring
+            # class in this campaign, after the bd audit's exclusion list.
+            if s.startswith("#[") and _is_test_attribute(s):
                 annotated = True
                 continue
             if s.startswith("fn ") or s.startswith("pub fn ") or s.startswith("async fn "):