chore: use generic placeholders in .env.local.example

Replace prefix-style placeholders with descriptive ones to avoid
confusion with real credentials.

Author: nicknisi

.env.local.example

@@ -2,8 +2,8 @@
 # Copy this to .env.local and fill in values
 
 # Required for running evals
-ANTHROPIC_API_KEY=sk-ant-...
+ANTHROPIC_API_KEY=your-anthropic-api-key
 
 # WorkOS credentials (optional for evals - placeholders used if missing)
-WORKOS_API_KEY=sk_test_...
-WORKOS_CLIENT_ID=client_...
+WORKOS_API_KEY=your-workos-api-key
+WORKOS_CLIENT_ID=your-workos-client-id