Desktop: update logged me out and wiped local communities

**Describe the bug**
A clear and concise description of what the bug is.

After updating Buzz today, I was signed out locally and lost my communities. Recovery was not “log back in.” I had to re-login, then go find invite links I had already sent out and click those just to get back into the same workspaces.

I have 2 communities of my own and I’m a member of 2 others. Doing that hunt-and-rejoin for all four was frustrating.

An update should not clear the local session or the community list.

What happened

Updated Buzz on 2026-08-21
Had to re-login
Local community list was gone
To get back in, I had to find old invite links I had sent and click them
4 communities total: 2 I have, 2 I belong to
Expected
Stay signed in across updates. Keep the local community list so I don’t have to rediscover and re-click invite links.

**Version and platform**
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- Buzz version: update to 0.5.18 (I think I had updated earlier today, not sure exactly the previous version)
- OS: mac os

**Logs / additional context**
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