Fix entrypoint: export DATA_DIR before exec

exec does not support inline VAR=value assignments in bash —
the shell was trying to execute the literal string as a binary.
DATA_DIR is already set on line 4, so just export it.

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

build/entrypoint.sh

@@ -19,4 +19,5 @@ echo "[entrypoint] Starting initial scrape in background..."
 bash /app/run_all.sh &
 
 echo "[entrypoint] Starting combined server on port 8080..."
-exec DATA_DIR="$DATA_DIR" python3 /app/server.py
+export DATA_DIR
+exec python3 /app/server.py