fix: refresh connection list after creating new connection

[datlechin]

Summary

• New connections created via the connection form didn't appear in the Welcome screen list until app restart
• The edit branch posted .connectionUpdated notification but the create branch did not
• Added the missing notification post to match the edit path

Test plan

• Open Welcome screen → New Connection → fill form → Create
• If connection fails, navigate back to Welcome — new connection should be visible in the list
• Edit an existing connection → Save → verify list still refreshes (regression check)