chore(claude): CLAUDE.md to avoid change detector tests

Author: sbalabanov-zz

CLAUDE.md

@@ -187,6 +187,7 @@ make clean              # Clean Bazel cache
 ### Testing
 
 - **Avoid asserting on error messages** — assert on error type or generic error.
+- **No change detector tests** — don't assert on default values, internal structure, or implementation details that can change without affecting behavior. Test what the code *does*, not how it's constructed.
 - **No `time.Sleep` for synchronization** — use channels, callbacks, condition variables.
 - **Use testify** — `assert`/`require` instead of `t.Fatal()`.