Various issues with special characters in searches

The following characters all cause errors:

(, ), ", '

Note that classic PonyMail can handle these.
It sanitises the strings using the following code:
escape_html( word:gsub("[()\"]+", "") )
i.e. () and " are eliminated, and the remainder is escaped.
This is done after the strings have been parsed, as the " chars are needed to delimit phrases

Start by locating the search parsing and sanitization entry point, then reproduce searches containing parentheses, double quotes, and single quotes. Done means these characters no longer cause errors while preserving phrase parsing and matching the classic PonyMail behavior described in the issue.

Written by the indexing model from the issue text.