The /uns filter was per-level: it matched only a node's direct children by
DisplayName and only under already-expanded nodes, so typing "blender" at the
top matched nothing — the structural ancestors don't contain the text and
weren't expanded.
Rework UnsTree to the standard tree-filter behaviour:
- A node is shown if it self-matches, sits under a matched ancestor, or has a
matching descendant (VisibleUnder).
- The path to a match auto-expands (chevron + child block follow a filter-
derived `childrenShown`, not node.Expanded), and the whole subtree under a
matched node is shown.
- Lazy tag children are only considered once their equipment is loaded, so the
filter never triggers lazy loads; the bounded structural tree keeps the
recursive walk cheap.
Clearing the filter restores the user's manual expand state (node.Expanded is
untouched). Build clean; AdminUI.Tests 216/216.
Joseph Doherty