feat: Exhibit A test execution harness

[JaeLeex]

Summary

• Adds runnable Exhibit A execution scripts: local MCP smoke, gateway smoke, Gate D dry run, and 5×5 workload experiment
• Adds funding_hedge_execute MCP tool (manifest had it; runner was missing)
• Documents A2.8 strategy def, A2.9 BLOCKED substitute, CI baseline, defects (D6), and updated tracker with automated results

Test plan

• pytest Exhibit A suite — 120 passed
• scripts/exhibit_a_mcp_smoke.py --section all — read + danger dry-run PASS
• scripts/mcp_workload_experiment.py --quick --dry-run — 5-agent pilot PASS
• Sam: run exhibit_a_gateway_smoke.sh with live EXHIBIT_A_MCP_TOKEN (mainnet minimal)
• Jacob: live A.3.7–A.3.8, A.4, A.5 per tracker BLOCKED rows

Made with Cursor

[sdb001]

Blocking issue: the advertised local MCP smoke command is not runnable from a fresh checkout. From repo root, python3 scripts/exhibit_a_mcp_smoke.py --section a2-read fails immediately with ModuleNotFoundError: No module named 'cli'. If I add PYTHONPATH=., it then fails with ModuleNotFoundError: No module named 'mcp'. Since this PR is specifically adding a runnable Exhibit A execution harness and marks scripts/exhibit_a_mcp_smoke.py --section all as passing, the script/runbook needs to either bootstrap the repo root onto sys.path and preflight the MCP extra with a clear install instruction, or the runbook must invoke it through an installed environment that guarantees yex-trader[mcp]. Verified compileall is clean and mcp_workload_experiment.py --quick --dry-run works.