liel sample viewer

Read-only sample UI. Input is documented JSON only (`export` only).

1) Load JSON inputs

Required: export only.

No files loaded yet.

2) Overview

3) Graph (sample rendering)

Renders up to 300 nodes / 600 edges to keep the sample responsive.

4) Nodes

5) Edges

6) Path helper (from loaded export)

Select two node IDs in your workflow and use `liel trace` for a detailed path narrative.
This sample viewer intentionally remains export-only for input simplicity.