nvidia-market: compare institution names on normalized form in Sheet 4 check

[bleonard]

Agents were scoring 0 on Sheet 4's institution checks while submitting the correct institutions. Groundtruth names are SEC-filing style (JPMORGAN CHASE & CO, BANK OF AMERICA CORP /DE/, GEODE CAPITAL MANAGEMENT, LLC), while agents write display-case names derived from the same data (JPMorgan Chase & Co., Bank of America Corp.). The check intersected raw strings, so a real failing run produced:

GT list: ['GEODE CAPITAL MANAGEMENT, LLC', 'JPMORGAN CHASE & CO']
ACT list: [..., 'Geode Capital Management, LLC', 'JPMorgan Chase & Co.', ...]
Intersection: [] (total 0)   <- required at least 1

The grader already normalizes shareholder names with normalize_str for Sheets 2–3; this PR applies the same normalization to the Sheet 4 intersection, additionally stripping SEC state-of-incorporation markers (/DE/) and a leading "The".

Replayed against the failing run's data: the "Continuous Increase" check goes 0 → 2 matches (now passes its ≥1 bar); "Top 5 Most Active" goes 1 → 2 (still under its ≥3 bar — those lists genuinely differ, so the check stays meaningful). Distinct institutions remain distinct under the normalization.