feat(menu): Google web search; note calc rework in the roadmap

The web module now opens google.com/search instead of DuckDuckGo. Also log
a roadmap item to rework calc: qalc -t misparses common phrasings (15% of
200 -> rem(15, 1 B)) and the result only shows in the next menu's -mesg
line -- move toward live results as you type.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/home/rofi.nix

@@ -106,7 +106,7 @@ let
       web)
         q=$(rofi -dmenu -p search < /dev/null) || exit 0
         [ -n "$q" ] || exit 0
-        exec xdg-open "https://duckduckgo.com/?q=$(urlencode "$q")" ;;
+        exec xdg-open "https://www.google.com/search?q=$(urlencode "$q")" ;;
 
       network)
         # nmtui in a terminal (NetworkManager is the system network stack).