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
Emil Shanaty
1314314567