Fix containing_function_name skipping inner class methods
`containing_function_name` was returning the nearest `def` going
backwards, which could be an inner class method (e.g. `__repr__`)
rather than the enclosing test function. This caused function-name
verification to fail, making `snapshot accept` error with
"Could not find inline= argument".
Fix by only considering `def` statements at strictly lower indentation
than the call site, which correctly skips inner definitions.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Remove narrating comments from tests, update CLAUDE.md
Strip inline comments that just narrate what the code does (e.g.,
"// Review: accept first, skip second"). Keep only comments that
explain non-obvious intent. Add CLAUDE.md rule against useless
inline comments in tests.