chore(security): enhance environment configuration, CI workflows, and wallet daemon with security improvements

- Restructure .env.example with security-focused documentation, service-specific environment file references, and AWS Secrets Manager integration
- Update CLI tests workflow to single Python 3.13 version, add pytest-mock dependency, and consolidate test execution with coverage
- Add comprehensive security validation to package publishing workflow with manual approval gates, secret scanning, and release

tests/e2e/fixtures/home/client1/.aitbc/config.yaml

@@ -0,0 +1,13 @@
+
+agent:
+  name: client1
+  type: client
+  wallet_path: ~/.aitbc/wallets/client1_wallet.json
+
+node:
+  endpoint: http://localhost:8082
+  timeout: 30
+
+coordinator:
+  url: http://localhost:8000
+  api_key: null