The `when` filter returns a <time> element, so title="{{ at|when }}" wrote raw
markup into the attribute. That broke the hover text, and in the rule form's
metric preview (#5475) it leaked a stray `">` into the page. `ago` already
carries the exact time as its own tooltip, so both places drop the title.
Also fixes #5467's page test, which needed the escaped apostrophe.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>