refactor(agent): unify process_direct to return OutboundMessage

Merge process_direct() and process_direct_outbound() into a single
interface returning OutboundMessage | None. This eliminates the
dual-path detection logic in CLI single-message mode that relied on
inspect.iscoroutinefunction to distinguish between the two APIs.

Extract status rendering into a pure function build_status_content()
in utils/helpers.py, decoupling it from AgentLoop internals.

Made-with: Cursor

tests/test_restart_command.py

@@ -175,14 +175,14 @@ class TestRestartCommand:
         assert "Context: 1k/64k (1%)" in response.content
 
     @pytest.mark.asyncio
-    async def test_process_direct_outbound_preserves_render_metadata(self):
+    async def test_process_direct_preserves_render_metadata(self):
         loop, _bus = _make_loop()
         session = MagicMock()
         session.get_history.return_value = []
         loop.sessions.get_or_create.return_value = session
         loop.subagents.get_running_count.return_value = 0
 
-        response = await loop.process_direct_outbound("/status", session_key="cli:test")
+        response = await loop.process_direct("/status", session_key="cli:test")
 
         assert response is not None
         assert response.metadata == {"render_as": "text"}