Exercise the mailu sync retry, attribute, and skip branches, the
listener non-object JSON path, and the hygiene conftest skip; drop the
unreachable inverted-range clamp in the semgrep report (the line helper
already floors the end line) and pin that behavior with a test. Exclude
the mailu __main__ guards from measurement.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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