Added Explainable AI agent demo in Typescript (#770)

(Not functional code)

dev-tools/explainable-ai/README.md

@@ -0,0 +1,29 @@
+# Explainable AI Demo
+
+Demonstrates the TrustGraph streaming agent API with inline explainability
+events. Sends an agent query, receives streaming thinking/observation/answer
+chunks alongside RDF provenance events, then resolves the full provenance
+chain from answer back to source documents.
+
+## What it shows
+
+- Streaming agent responses (thinking, observation, answer)
+- Inline explainability events with RDF triples (W3C PROV + TrustGraph namespace)
+- Label resolution for entity and predicate URIs
+- Provenance chain traversal: subgraph → chunk → page → document
+- Source text retrieval from the librarian using chunk IDs
+
+## Prerequisites
+
+A running TrustGraph instance with at least one loaded document and a
+running flow. The default configuration connects to `ws://localhost:8088`.
+
+## Usage
+
+```bash
+npm install
+node index.js
+```
+
+Edit the `QUESTION` and `SOCKET_URL` constants at the top of `index.js`
+to change the query or target instance.