feat(dashboard): manage route chains in a floating window with per-account model catalog Virtual model and auto cards on the Routing screen become read-only; the "Manage" window edits the chain (drag from the catalog, reorder, params). The catalog groups models by account, filters by account and accepts regex search; available-models now returns key_labels per model. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> - #494