5.3. The final steps
The theorem eventual_sign_of_not_zerosAboveEveryHeight gives a constant sign beyond the zeros.
The theorem tendsto_normalizedHardyIntegral proves the vanishing integral limit.
The theorem not_positive_tail_of_vanishing_differences gives the integral contradiction.
The theorem zerosAboveEveryHeight proves the existence of zeros above every height.
The theorem hardy proves the exact infinitude statement.