feat(self-heal): wire the dormant orchestrator loop

Register _self_heal_loop alongside the other background loops (created in
start, cancelled in stop). It returns immediately unless self_heal_enabled, so
a standard deployment adds zero behaviour and makes no CI call; when on it runs
one engine cycle per interval and commits any opened fix task. A test pins the
default-off dormancy (no sleep / CI / DB when disabled).

tests/unit/runtime/test_self_heal_loop_dormant.py

@@ -0,0 +1,26 @@
+"""The self-heal orchestrator loop is fully dormant when disabled (the default).
+
+With ``self_heal_enabled`` off, ``_self_heal_loop`` must return immediately —
+no sleep, no CI call, no DB — so a standard deployment behaves exactly as today.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import types
+from typing import cast
+
+import pytest
+from roboco.config import settings as cfg
+from roboco.runtime.orchestrator import AgentOrchestrator
+
+
+@pytest.mark.asyncio
+async def test_self_heal_loop_returns_immediately_when_disabled(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(cfg, "self_heal_enabled", False)
+    stub = cast("AgentOrchestrator", types.SimpleNamespace(_running=True))
+    # Gated off → returns at once. If the gate were missing it would sleep the
+    # full interval and this wait_for would time out.
+    await asyncio.wait_for(AgentOrchestrator._self_heal_loop(stub), timeout=1.0)