preact 05-discovery: TypeIndex discovery + Tasks view

  - fetchTypeIndex(webid): pulls WebID, follows solid:publicTypeIndex,
    walks any node with solid:forClass + (instance|instanceContainer)
    no matter where it lives (schema:itemListElement, @graph, scattered).
  - useTypeIndex / useInstances hooks compose the discovery + fetch.
  - TasksView: discovers wf:Tracker registrations, fetches each, renders
    title + issues with COMPLETED / NEEDS-ACTION badges.
  - Settings: adds a TypeIndex registrations card showing the live
    registration list — debug aid for what the pod actually exposes.

Tested against melvin.me which serves JSON-LD natively. Pods that only
serve Turtle would need a parser (not added here).

Author: melvincarvalho