feat: add agent workflow metrics collection

Add comprehensive OpenTelemetry-based metrics for agent observability:

- Workflow completion/failure tracking with duration measurements
- Step execution counters for performance monitoring
- Tool usage tracking with normalized tool names
- Non-blocking telemetry emission with named async tasks
- Comprehensive unit and integration test coverage
- Graceful handling when telemetry is disabled

tests/integration/agents/test_agent_metrics_integration.py

@@ -0,0 +1,59 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import asyncio
+from unittest.mock import AsyncMock, Mock, patch
+
+from llama_stack.providers.inline.agents.meta_reference.agent_instance import ChatAgent
+
+
+class TestAgentMetricsIntegration:
+    """Smoke test for agent metrics integration"""
+
+    async def test_agent_metrics_methods_exist_and_work(self):
+        """Test that metrics methods exist and can be called without errors"""
+        # Create a minimal agent instance with mocked dependencies
+        telemetry_api = AsyncMock()
+        telemetry_api.logged_events = []
+
+        async def mock_log_event(event):
+            telemetry_api.logged_events.append(event)
+
+        telemetry_api.log_event = mock_log_event
+
+        agent = ChatAgent(
+            agent_id="test-agent",
+            agent_config=Mock(),
+            inference_api=Mock(),
+            safety_api=Mock(),
+            tool_runtime_api=Mock(),
+            tool_groups_api=Mock(),
+            vector_io_api=Mock(),
+            telemetry_api=telemetry_api,
+            persistence_store=Mock(),
+            created_at="2025-01-01T00:00:00Z",
+            policy=[],
+        )
+
+        with patch("llama_stack.providers.inline.agents.meta_reference.agent_instance.get_current_span") as mock_span:
+            mock_span.return_value = Mock(get_span_context=Mock(return_value=Mock(trace_id=123, span_id=456)))
+
+            # Test all metrics methods work
+            agent._track_step()
+            agent._track_workflow("completed", 2.5)
+            agent._track_tool("web_search")
+
+            # Wait for async operations
+            await asyncio.sleep(0.01)
+
+            # Basic verification that telemetry was called
+            assert len(telemetry_api.logged_events) >= 3
+
+            # Verify we can call the methods without exceptions
+            agent._track_tool("knowledge_search")  # Test tool mapping
+            await asyncio.sleep(0.01)
+
+            assert len(telemetry_api.logged_events) >= 4