verbose live UI + tool-level SSE events + Groq default + regression tests

.env.example

@@ -4,6 +4,9 @@
 # Warehouse
 DATABASE_URL=postgresql://nvi:nvi@postgres:5432/nvi
 
+# Active dataset (selects api/datasets/<name>/ + Postgres schema + sqlite file).
+NVI_DATASET=financial
+
 # LLM
 ANTHROPIC_API_KEY=
 ANTHROPIC_MODEL=claude-sonnet-4-6