[FEATURE]: Add a config to set the sidebar to open/closed by default

[spahl]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

In smaller windows the sidebar takes up a bit of space.

Add a config option to set the default state (open or closed) by default.

[spahl]

@thdxr replying here. No worries at all. Makes a lot of sense. Want me to take a stab at it? No problem if you'd rather do it yourself.

[marcelarie]

I vibe coded a solution, just for the TUI, and created a PR (#6955)

[dhruvkej9]

@thdxr This is much needed feature please merge it