[Bug]: Tab background setting resets if you close only tab #3517

Current Behavior

You have a wave window with only the default tab open (Terminal 1). if you chose a background for that tab via right click and ten close the tab (thus, closing the app), next time you open the app the tab defaults to the black bakground. Even setting a custom background doesnt apply it to the default tab

Settings:

{
  "autoupdate:channel": "latest",
  "tab:background": "bg@ocean-depths-deep",
  "term:copyonselect": false,
  "term:fontsize": 16,
  "term:theme": "basic-balanced-dark"
}

Expected Behavior

Tab background applies to all tabs independent on how you close them or if its the last one

Steps To Reproduce

1. Open wave terminal
2. set a tab background (any)
3. close the tab (this closes the app)
4. reopen the app, tab bg reverts to default

Wave Version

Client Version 0.14.5 (202604161535)

Platform

Linux

OS Version/Distribution

Ubuntu 26.04.1

Architecture

x64

Anything else?

No response