fix(app): use local SVG avatar to fix broken Gradio icon

Remote DiceBear URL in avatar_images fails on network errors and CORS.
Replace with assets/flame.svg. Also document gradio run command in CLAUDE.md.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -59,6 +59,9 @@ uv run python scripts/build_graph.py
 
 # 5. Build ChromaDB vector index
 uv run python scripts/build_index.py
+
+# 6. run application
+uv run gradio app.py
 ```
 
 ## Key Invariants

app.py

@@ -129,7 +129,7 @@ with gr.Blocks(title="Candle-Fire — ALS Research Intelligence") as demo:
             height=520,
             show_label=False,
             sanitize_html=False,
-            avatar_images=(None, "https://api.dicebear.com/7.x/icons/svg?seed=candle&icon=flame"),
+            avatar_images=(None, "assets/flame.svg"),
             placeholder="Ask a question about ALS research to get started.",
         )