Powerline font detection misses Nerd Fonts v3 names, the NF short form, and fonts in subfolders #738

What you see

With a Nerd Font v3 installed (the current Nerd Fonts release naming), the TUI's Powerline Setup reports Font Status: ✗ Not Installed - Press (i) to install Powerline fonts, and the status message says fonts are not detected — although the terminal draws the Powerline glyphs fine. The same font file is detected under its old v2 name; only its name differs:

How to reproduce

1. Put JetBrainsMonoNerdFont-Regular.ttf (Nerd Fonts v3, e.g. the Homebrew font-jetbrains-mono-nerd-font cask) in ~/Library/Fonts/ on macOS or ~/.local/share/fonts/ on Linux.
2. Open the TUI → Powerline Setup: it reports "✗ Not Installed".
3. Rename the same file to the old v2 style, JetBrains Mono Regular Nerd Font Complete.ttf, and the status flips to "✓ Installed".

Why

checkPowerlineFonts (src/utils/powerline.ts) is a top-level readdirSync of the font folders matched against file-name patterns. It misses common setups:

• Nerd Fonts v3 file names have no space. /nerd font/i does not match JetBrainsMonoNerdFont-Regular.ttf, HackNerdFont-Regular.ttf or CaskaydiaCoveNerdFont-Regular.ttf.
• The short v3 form is not matched either. JetBrainsMonoNF-Regular.ttf.
• Fonts in subfolders are never seen. For example ~/.local/share/fonts/NerdFonts/..., /usr/share/fonts/TTF/..., or /usr/share/fonts/opentype/PowerlineSymbols.otf from the Debian fonts-powerline package.

This also affects the font-safe separator fallback proposed in #604: keyed on this detection, it would replace the Powerline glyphs with | for all of these setups. The fork hit exactly that after implementing the fallback (live repro and discussion: axisrow#62; the screenshot above is from there). The closed #56 is symptom-adjacent but has a different cause.

Fix

Proposed in a PR to follow immediately: match nerd ?font and an NF token, and scan the font folders recursively (depth-capped).

Follow-up (out of scope here)

• Terminals with built-in Powerline glyphs (Ghostty, kitty, WezTerm) have no font file to find, so they will still be reported as "not installed". I don't have these terminals and can't verify such a change, so I'm leaving it to someone who does.
• The two checks use different matchers. Powerline Setup shows the async fc-list | grep -i powerline status, while the sync file-name scan drives the rest; on a machine with both a Powerline-named font and a v3 Nerd Font the two places can disagree.