Enhance game setup for VM and standalone modes

- Updated `GamesController` to use `current_player` for VM set retrieval.
- Improved `MissionsController` to handle redirection for both Hacktivity and standalone modes.
- Modified `new.html.erb` to include UI for standalone flag input alongside VM set selection.
- Added new CSS styles for standalone mode instructions and flags input form.
- Introduced new mission configuration for the SecGen VM Lab, integrating VM and flag capture elements.

app/controllers/break_escape/games_controller.rb

@@ -11,7 +11,7 @@ module BreakEscape
       authorize @mission, :create_game? if defined?(Pundit)
 
       if @mission.requires_vms?
-        @available_vm_sets = @mission.valid_vm_sets_for_user(current_user)
+        @available_vm_sets = @mission.valid_vm_sets_for_user(current_player)
         @existing_games = Game.where(player: current_player, mission: @mission)
       end
     end

app/controllers/break_escape/missions_controller.rb

@@ -20,10 +20,11 @@ module BreakEscape
       @mission = Mission.find(params[:id])
       authorize @mission if defined?(Pundit)
 
-      if @mission.requires_vms? && BreakEscape::Mission.hacktivity_mode?
-        # VM missions need explicit game creation with VM set selection
-        # Redirect to games#new which shows VM set selection UI
-        # Use explicit path instead of route helper to ensure it works in engine context
+      if @mission.requires_vms?
+        # VM missions (Hacktivity or standalone) need explicit setup
+        # Redirect to games#new which shows appropriate UI:
+        # - Hacktivity mode: VM set selection
+        # - Standalone mode: Flag input form
         redirect_to "/break_escape/games/new?mission_id=#{@mission.id}"
       else
         # Legacy behavior for non-VM missions - auto-create game