Sidebar caret column is wider than its caret

Owner (2026-11-03): the space for the expand caret in sidebar rows is a bit too big. The caret column (--sidebar-caret-width in apps/web/src/components/sidebar/SidebarColumns.css) is 1.5rem for a 1rem caret. Narrow it a little; carets and icons must still line up across rows, and two-digit counts must still fit.

Was Forgejo issue #320.

fix(server): GitLab issue host typechecks against effect 4.0.5