Root cause: SQLite uses BINARY collation, so WHERE name = ? is
case-sensitive. When changing 'john doe' to 'John Doe', the name
lookup failed and fell through to the email path which didn't update
the name. The previous fix only added UPDATE in the name-match branch.
Fixes in findOrCreateAuthor:
1. Accept optional $idHint parameter — when known (edit flow), update
directly by ID (fastest, zero ambiguity)
2. Add COLLATE NOCASE to the name lookup (fallback path)
3. Add UPDATE in the email fallback path too
setThesisAuthors now fetches existing author_ids before deletion and
passes them as position-based hints, so identity is always preserved.
