build(agent-job): pin Claude Code CLI; smoke one turn per runtime

Add @anthropic-ai/claude-code@2.1.207 to the job image global npm install,
extend the smoke script with claude --version plus a documented per-runtime
turn block, and reconcile OpenCode/Claude adapter flags against the real CLIs
(all assumed flags confirmed). Document the anthropic_oauth_json credential
snapshot pattern in the README.

scripts/smoke-agent-container

@@ -28,4 +28,16 @@ fi
   python3 --version
   opencode --version
   codex --version
+  claude --version
 '
+
+# Manual per-runtime smoke (requires creds in your shell env):
+#   docker build -f docker/agent-job.Dockerfile -t spoon-agent-job:latest .
+#   docker run -d --name spoon-box-smoke --init spoon-agent-job:latest sleep infinity
+#   docker exec -e OPENAI_API_KEY -w /workspace spoon-box-smoke \
+#     opencode run --format json --model openai/gpt-5.5 -- 'print hello'
+#   docker exec -e ANTHROPIC_API_KEY -w /workspace spoon-box-smoke \
+#     claude -p 'print hello' --output-format stream-json --verbose --dangerously-skip-permissions
+#   docker exec -e CODEX_HOME=/root/.codex -w /workspace spoon-box-smoke \
+#     codex exec --json --dangerously-bypass-approvals-and-sandbox 'print hello'
+#   docker rm -f spoon-box-smoke