Tesria 0.8.7

A small update: the clear button an exported site's page filter was missing,
and the page tree's drag library brought up to date.

• Fixed: an exported site's page filter had no clear button. The app's
  filter gained one in 0.8.1, but the site's sidebar is built separately and
  was missed, and the stylesheet hides the browser's own. It now has the
  same button, beside the Show the Pages Under Each Match toggle. Checked on
  a real export of the docs, Minimal and Glass, light and dark, on a phone
  and a desktop, on the front page and a content page.
• Dependencies: @dnd-kit/sortable 10 (was held at 9 in 0.8.4 until the
  page tree's drag to reorder was checked on it). Checked by hand on an
  iPhone and in Chrome on Windows. Its only change is requiring
  @dnd-kit/core 6.3 or later, which Tesria already uses.