feat: add setup notebook and update env example for Athena

.env.example

@@ -1,10 +1,12 @@
-# Athena API
-ATHENA_BASE_URL=https://athena.nttdata.com
+# Copy to .env (gitignored) and fill in — or just run 00_setup.ipynb,
+# which prompts for these and writes .env for you.
+ATHENA_BASE_URL=https://athena.ouranos.helu.ca
 ATHENA_API_KEY=your-api-key-here
 
 # Optional — pre-set the active study + tool so notebooks/CLI pick them up
-# without editing config.py.
-#
+# without editing config.py. 00_provision.ipynb writes these for you.
+# A TEI tool attaches to exactly ONE of proposal / engagement.
 # PALLADIUM_REPORT_PUBLIC_ID=
 # PALLADIUM_TOOL_PUBLIC_ID=
 # PALLADIUM_PROPOSAL_ID=
+# PALLADIUM_ENGAGEMENT_ID=