cleanup localStorage in web dashboard

**Describe the bug**

Over time, localhost:3001 may accumulate enough data in localStorage that the browser blocks it from storing any more, and the logs stop appearing in the UI.

**To Reproduce**

Spam via the web dashboard for several days.

**Expected behavior**

Logs should be cleared out whenever a session is removed, or the connection from the webpage to the webserver is dropped.

Start at the web dashboard served through localhost:3001 and trace where localStorage records are written, sessions are removed, and the webpage connection is dropped. Reproduce the multi-day or repeated-use scenario, then verify that stored logs are cleared in both cleanup cases and continue appearing in the UI.

Written by the indexing model from the issue text.