Fail closed on policy runtime outages

[kebanks2]

/claim #3592

Summary

• adds a dependency-light PolicyRuntime that fails closed when the policy engine is unavailable or the evaluator raises
• records policy-denied tasks as terminal failed outcomes before hooks, agent status mutation, or dispatch side effects
• clears in-flight state, preserves the same task id across bounded retries, and skips duplicate terminal executions
• exports AgentStatus and fixes the existing metrics timer self-deadlock so the full local suite can complete

Validation

• /tmp/ao-3592-venv/bin/python -m pytest tests -q -> 28 passed
• /tmp/ao-3592-venv/bin/python -m flake8 src/common/policy.py src/common/metrics.py src/orchestrator/engine.py src/orchestrator/scheduler.py src/agent/__init__.py tests/test_policy_runtime.py
• /tmp/ao-3592-venv/bin/python -m py_compile src/common/policy.py src/common/metrics.py src/orchestrator/engine.py src/orchestrator/scheduler.py src/agent/__init__.py tests/test_policy_runtime.py
• git diff --check
• gh repo view orchestration-agent/AgentOrchestration --json viewerHasStarred --jq '.viewerHasStarred' -> true

No secrets, tokens, hidden context, private runtime data, or payout details are included.