feat: conformance test runner + protocol fixes

- conformance.py: declarative scenario runner (subset matcher, $kind/$gt/
  $enum/$required assertions, call_id/session_id echo checks), reference
  bridge, CLI entry (python -m aicc.conformance)
- bridge.py: protocol version check before parsing (protocol_mismatch),
  session expiry handling (session_expired), malformed tool_call ->
  invalid_input, emit_event() for async events
- client.py: Self return type
- in_process.py: drain bridge event queue after response (event delivery),
  Self return type
- websocket.py: Self return type, best-effort shutdown
- tests: 14 passing (incl. conformance scenarios, 9/9 core scenarios)
- ruff: all checks pass

tests/test_conformance.py

@@ -0,0 +1,33 @@
+"""Conformance runner tests: runs the declarative scenarios from the spec repo."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+from aicc.conformance import reference_bridge, run_scenarios, summarize
+
+SCENARIOS = Path(__file__).resolve().parents[1] / ".." / "aicc-spec" / "conformance" / "scenarios"
+
+
+@pytest.mark.asyncio
+async def test_core_scenarios_pass():
+    if not SCENARIOS.exists():
+        pytest.skip("AICC-Protocol conformance scenarios not found on this machine")
+    bridge = reference_bridge()
+    results = await run_scenarios(bridge, SCENARIOS)
+    report = summarize(results)
+    assert all(r.passed for r in results), report
+
+
+@pytest.mark.asyncio
+async def test_runner_rejects_unknown_tool():
+    """A bridge missing a required tool fails the corresponding scenario."""
+    from aicc import Bridge
+
+    bridge = Bridge(name="incomplete")
+    results = await run_scenarios(bridge, SCENARIOS)
+    by_id = {r.id: r for r in results}
+    # echo tool missing -> core-03 must fail
+    assert not by_id["core-03-tool-call-ok"].passed

tests/test_integration.py

@@ -2,8 +2,6 @@
 
 from __future__ import annotations
 
-import asyncio
-
 import pytest
 
 from aicc import AICCClient, Bridge, ToolClass

tests/test_websocket.py

@@ -2,8 +2,6 @@
 
 from __future__ import annotations
 
-import asyncio
-
 import pytest
 
 from aicc import AICCClient, Bridge