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

aicc/__init__.py

@@ -1,45 +1,45 @@
 """aicc-py: Python SDK for the AI-Controlled Character Protocol."""
 
-from aicc.protocol import (
-    ErrorCode,
-    MessageType,
-    TickMode,
-    WorldKind,
-    ModelClass,
-    ToolClass,
-    SessionInit,
-    SessionClose,
-    ToolCall,
-    ToolResult,
-    EventMessage,
-    ErrorMessage,
-    Heartbeat,
-)
-from aicc.errors import AICCError, ToolError, CapabilityError, ProtocolError
 from aicc.bridge import Bridge
 from aicc.client import AICCClient
+from aicc.errors import AICCError, CapabilityError, ProtocolError, ToolError
+from aicc.protocol import (
+    ErrorCode,
+    ErrorMessage,
+    EventMessage,
+    Heartbeat,
+    MessageType,
+    ModelClass,
+    SessionClose,
+    SessionInit,
+    TickMode,
+    ToolCall,
+    ToolClass,
+    ToolResult,
+    WorldKind,
+)
 from aicc.tool import tool
 
 __version__ = "0.1.0"
 __all__ = [
-    "Bridge",
     "AICCClient",
-    "tool",
-    "ErrorCode",
-    "MessageType",
-    "TickMode",
-    "WorldKind",
-    "ModelClass",
-    "ToolClass",
-    "SessionInit",
-    "SessionClose",
-    "ToolCall",
-    "ToolResult",
-    "EventMessage",
-    "ErrorMessage",
-    "Heartbeat",
     "AICCError",
-    "ToolError",
+    "Bridge",
     "CapabilityError",
+    "ErrorCode",
+    "ErrorMessage",
+    "EventMessage",
+    "Heartbeat",
+    "MessageType",
+    "ModelClass",
     "ProtocolError",
+    "SessionClose",
+    "SessionInit",
+    "TickMode",
+    "ToolCall",
+    "ToolClass",
+    "ToolError",
+    "ToolResult",
+    "WorldKind",
+    "tool",
 ]