feat: observable tasks categories

src/JsonRPCNotificationError.php

src/JsonRPCResponseError.php

src/ObservableTask.php

src/ObservableTaskInterface.php

src/ObservableTaskStatusUpdate.php

src/ObservableTaskTable.php

src/ObservableTaskTableRow.php

src/Session.php

...JsonRPCResponder/LlamaCppSubjectActionPromptResponder.php

src/views/observable_tasks_dashboard.twig