[Muguett-DBY]

Fixes #922.

FTS4 needs the old content row to be available when it removes an index entry. This uses BEFORE DELETE and BEFORE UPDATE triggers for that removal, followed by an AFTER UPDATE trigger to index the new values. The existing FTS5 triggers are unchanged.

replace=True recreates older FTS4 trigger sets, and disable_fts() now also removes DELETE-based triggers while handling quoted names and SQL wildcard characters safely.

Testing:

• The full pytest suite passed on Windows, Python 3.12.14 and SQLite 3.53.1 with UTF-8 mode enabled: 1,505 passed, 17 skipped, 32 warnings.
• Black 26.3.1 passed for the three changed files.
• mypy sqlite_utils tests passed with the project configuration (mypy 2.4.1).
• The repository-wide flake8 check passed (flake8 7.5.0).
• Restoring the original FTS methods caused seven of 56 selected tests to fail (the five filesystem-fixture tests were not included in that comparison).

I used Codex to help investigate and implement this fix, and reviewed the changes and test results.