[Feature]: Allow configuring the tab bar font family

[amitbsen]

Feature description

term:fontfamily in settings.json controls the terminal pane font, but the tab bar ignores it. The tab bar inherits "Inter" from the --base-font CSS variable in theme.scss, and no setting exists to change it.

I use a monospace font in my terminal and would like the tab labels to match (or at least use a font I choose). Right now the only way to do this is to fork the repo and edit theme.scss directly.

A tab:fontfamily setting would let users control the tab bar font through the same settings.json mechanism that already handles term:fontfamily, ai:fontsize, and editor:fontsize.

Implementation Suggestion

The existing font settings follow a consistent pattern. A new tab:fontfamily key could work the same way:

1. Add ConfigKey_TabFontFamily = "tab:fontfamily" to pkg/wconfig/metaconsts.go, alongside the existing term:fontfamily constant.
2. Read the setting in the tab component (frontend/app/tab/tab.tsx) and apply it as an inline fontFamily style on the .name div, falling back to the current inherited "Inter" when unset.
3. Optionally, a tab:fontsize key could accompany it, since the tab name currently hardcodes font-size: 11px in tab.scss.

This mirrors how term:fontfamily feeds into xterm.js options in frontend/app/view/term/term.tsx.

Anything else?

Related: #2136 requests broader UI font customization. This issue is narrower and focuses on the tab bar specifically, which is the most visible piece of UI chrome that users cannot currently restyle.