AO3-6348 Fix autocomplete highlight escaping for pipe queries

[noahbravo]

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Issue

https://otwarchive.atlassian.net/browse/AO3-6348

Purpose

Fixes an autocomplete highlighting issue where queries containing a pipe (|) can result in malformed suggestions with a stray semicolon after ampersands.

For example, typing Evil Queen | could produce:
Evil Queen | Regina Mills &; Henry Mills
instead of:
Evil Queen | Regina Mills & Henry Mills

This was caused by incomplete escaping of regex metacharacters in the autocomplete highlighting logic.

Changes made:

• Updated regex escaping in public/javascripts/jquery.tokeninput.js to correctly escape | and other metacharacters.
• Updated public/javascripts/jquery.tokeninput.min.js accordingly.
• Added a JavaScript feature scenario in features/other_a/autocomplete.feature to cover this case.

Testing Instructions

Automated:

• docker compose run --rm test bundle exec cucumber features/other_a/autocomplete.feature:264
• docker compose run --rm test bundle exec cucumber features/other_a/autocomplete.feature

Manual:
Follow the reproduction steps in AO3-6348:
https://otwarchive.atlassian.net/browse/AO3-6348

Expected behavior:

• Autocomplete suggestions should not include a stray semicolon after ampersands when the query contains a pipe (|).
• The example relationship should appear as:
  Evil Queen | Regina Mills & Henry Mills
• No regressions in other autocomplete fields.

Credit

Name: Noah Bravo
Pronouns: they/them

[brianjaustin]

Thanks!