fix(wiki): stop the page list rebuilding on every autosave

[github-actions]

The nav flash persisted after the sidebar-rail fix because this is a second,
separate offender in a different element. The rail fix (workspace.js) was real;
it just was not the thing flashing here.

wiki.js flushSave updates one row's data and then calls renderPageList(), which
opens with tree.innerHTML = "" and rebuilds every row. Off a 500ms autosave
debounce that is a full teardown of the wiki page list every time typing pauses.
The existing comment says "update the row in the list without re-fetching the
whole index" — it avoids the fetch but still does the full DOM rebuild.

A row renders exactly two things, the title and relTime(updated_at), and both
belong to the row being saved. So patch that row in place: rows now carry
data-page-id, and the save path updates the title and meta text directly. Falls
back to renderPageList() when the row is not found (list not built yet, or a
newly added page), so structural changes still repaint.

Note this is deliberately NOT the diff-and-skip approach used for the rail:
updated_at genuinely changes on every save, so the meta text really does need
updating. Skipping would be wrong; rebuilding everything was just overkill.

Used a dataset scan rather than a CSS.escape selector — it would have been the
only CSS.escape in the codebase, and page ids are UUIDs, so the escaping bought
nothing and added a first-and-only browser dependency.

esprima parses wiki.js. Whether the flash is gone is a repaint, which only the
operator can confirm on desktop.

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Opened automatically after the tiers check passed on d1c1aa29.

The check is attached to this branch head, so this is mergeable now.