feat(tournaments): add partnership tracking and tournament management

Implement comprehensive partnership tracking system and tournament
management features including round-robin, single/double elimination,
and Swiss system pairings.

Changes:
- Add partnership_games and partnership_stats tables
- Implement PartnershipTracker service for recording partnership data
- Add tournament generator with multiple formats
- Create tournament management actions and views
- Add acceptance tests for partnership tracking
- Fix PartnershipTracker to use single snapshot per player per match
- Fix round-robin test to query by round_number instead of hardcoded ID

Note: All 8 acceptance tests now passing

app/actions/admin/tournaments/create.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module EuchreCamp
+  module Actions
+    module Admin
+      module Tournaments
+        class Create < EuchreCamp::Action
+          include Deps[repo: 'repositories.events']
+
+          def handle(request, response)
+            params = request.params.to_h
+
+            event_params = {
+              name: params[:name],
+              description: params[:description],
+              event_date: params[:event_date] ? Time.parse(params[:event_date]) : nil,
+              event_type: 'tournament',
+              format: params[:format] || 'single_elim',
+              status: 'planned',
+              max_participants: params[:max_participants]&.to_i
+            }
+
+            event = repo.create(event_params)
+
+            response.redirect_to("/admin/tournaments/#{event[:id]}")
+          rescue StandardError => e
+            response.flash[:error] = "Failed to create tournament: #{e.message}"
+            response.redirect_to("/admin/tournaments/new")
+          end
+        end
+      end
+    end
+  end
+end