chore: document observable task table

composer.json

composer.lock

docs/pages/docs/features/observability/index.md

...ocs/features/observability/observable-task-table/index.md

src/HttpResponder/ObservableTasksDashboard.php

src/ObservableTaskTable.php

src/ObservableTaskTableTest.php

src/SiteAction.php

...JsonRPCResponder/LlamaCppSubjectActionPromptResponder.php

...tJsonRPCResponder/ObservableTasksTableUpdateResponder.php

src/views/observable_tasks_dashboard.twig