fix(sefariasqlite): resolve authors with an empty Hebrew name

[kdroidFilter]

Fixes kdroidFilter/Zayit#444

Problem

Sefaria ships some authors with an empty he title — Admat Kodesh's author is {"en": "Nissim Chaim Moshe Mizrachi", "he": "", ...} (same in their topics API). The reader stored the empty string, so the book had a blank author. In the current export, 11 authors / 16 books are affected (Sefer HaIkkarim, Shem MiShmuel, Rav Nissim Gaon, Be'er Sheva, Epistle of Rav Sherira Gaon, …).

Fix

resolveSefariaAuthorName resolves each authors entry from:

1. the he title when non-blank,
2. a Hebrew override keyed by Sefaria topic slug (the 11 known cases),
3. the English name,

and drops the author when none is usable.

Tests

SefariaAuthorNamesTest covers each branch.