chore: scaffold arcade-eval repo skeleton

config/.env.example

@@ -0,0 +1,16 @@
+# Arcade eval credentials — copy to .env (git-ignored) and fill in.
+# Load with: set -a && . ./.env && set +a
+
+ARCADE_API_BASE=https://api.arcade.st.dev
+ARCADE_DASHBOARD=https://dashboard.arcade.st.dev
+
+# Project API key — minted in the dashboard (Phase 1, Task 1.1). Never commit the real value.
+ARCADE_API_KEY=
+
+# Headless per-user identity — the vault is keyed on the user_id string you pass.
+# One API key can present as many users. (Real Entra SSO login is a cat-2 concern.)
+ARCADE_USER_A=user-a@servicetitan.com
+ARCADE_USER_B=user-b@servicetitan.com
+
+# The exact header name(s) for API-key + user_id on MCP calls are CONFIRMED live in Task 1.1
+# and recorded in LIVE-POC.md — do not guess them in code.