Unset BROWSER for xdg-settings reads and don't abort removal on fallback failure

xdg-settings get also consults $BROWSER, so unset it for the getters too.
A failed best-effort fallback default should not abort the browser removal.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

bin/omarchy-launch-browser

@@ -3,7 +3,7 @@
 # omarchy:summary=Launch the default browser as determined by xdg-settings.
 # omarchy:args=[url]
 
-default_browser=$(xdg-settings get default-web-browser)
+default_browser=$(env -u BROWSER xdg-settings get default-web-browser)
 browser_exec=$(sed -n 's/^Exec=\([^ ]*\).*/\1/p' {~/.local,~/.nix-profile,/usr}/share/applications/$default_browser 2>/dev/null | head -1)
 
 if $browser_exec --help 2>/dev/null | grep -q MOZ_LOG; then