nushell: Use tkey-ssh-agent if installed

tree/.config/nushell/env.nu

@@ -85,7 +85,13 @@ $env.PATH = ($env.PATH | split row (char esep) | prepend [
     ($env.HOME + "/.volta/bin"),
 ])
 
+# auto-detect which ssh-agent to use
+if (which tkey-ssh-agent | is-empty) {
     $env.SSH_AUTH_SOCK = $"($env.XDG_RUNTIME_DIR)/ssh-agent.socket"
+} else {
+    $env.SSH_AUTH_SOCK = $"($env.XDG_RUNTIME_DIR)/tkey-ssh-agent/sock"
+}
+
 $env.GPG_TTY = (tty)
 $env.BROWSER = "firefox"
 $env.EDITOR = "nvim"