fix: #3361 honor session settings in AsyncSQLiteSession

[Aphroq]

Summary

Add session_settings support to AsyncSQLiteSession and resolve get_items(limit=None) through the shared session limit helper.

This aligns async SQLite with the other session backends while preserving existing constructor positional compatibility by appending the optional parameter.

Test plan

• uv run pytest tests/extensions/memory/test_async_sqlite_session.py -q
• bash .agents/skills/code-change-verification/scripts/run.sh

The focused async SQLite session tests pass on this branch directly. The full shell verification script was run in a local validation checkout where this branch was temporarily combined with the pending tracing shutdown fix, so the tracing atexit cleanup test would not time out.

Issue number

Closes #3361

Checks

• I've added new tests (if relevant)
• I've run make lint and make format
• I've made sure tests pass