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-remove-browser

@@ -7,14 +7,14 @@
 
 set_fallback_default_browser() {
   local current_browser
-  current_browser=$(xdg-settings get default-web-browser)
+  current_browser=$(env -u BROWSER xdg-settings get default-web-browser)
 
   if [[ $current_browser != $1 ]]; then
     return
   fi
 
   if omarchy-cmd-present chromium; then
-    env -u BROWSER xdg-settings set default-web-browser chromium.desktop || exit 1
+    env -u BROWSER xdg-settings set default-web-browser chromium.desktop || true
   fi
 }