Detect uninstalled model plugins for LLM nodes in the checklist and
publish-gate. Migrate ChecklistItem.errorMessage to errorMessages[]
so a single node can surface multiple validation issues at once.
- Extract shared extractPluginId utility for checklist and prompt editor
- Build installed-plugin Set (O(1) lookup) from ProviderContext
- Remove short-circuit between checkValid and variable validation
- Sync the same check into handleCheckBeforePublish
- Adapt node-group, use-last-run, and test assertions
Migrate checklist from flat card list using deprecated PortalToFollowElem to
grouped tree view using base-ui Popover. Split into checklist/ directory with
separate components: plugin group with batch install, per-node groups with
sub-items and "Go to fix" hover action, and tree-line SVG indicators.
