Add Elo rating system with match entry and CSV upload

- Implement EloCalculator service for 2v2 Euchre matches
- Create background job processing with GoodJob
- Add single match entry form
- Add CSV upload for batch match entry
- Create player rankings view
- Add database schema for matches and elo snapshots

app/actions/players/rankings.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module EuchreCamp
+  module Actions
+    module Players
+      class Rankings < EuchreCamp::Action
+        include Deps[repo: 'repositories.players']
+
+        def handle(_request, response)
+          # Get all players and sort by current Elo
+          players = repo.all.sort_by { |p| -p.current_elo }
+          response.render(view, players: players)
+        end
+      end
+    end
+  end
+end