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/repositories/partnership_stats.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require 'rom-repository'
+
+module EuchreCamp
+  module Repositories
+    class PartnershipStats < ::EuchreCamp::Repository[:partnership_stats]
+      commands :create, update: :by_pk
+
+      def find_or_create(player_1_id, player_2_id)
+        # Ensure consistent ordering (lower ID first)
+        p1_id = [player_1_id, player_2_id].min
+        p2_id = [player_1_id, player_2_id].max
+
+        stats = partnership_stats.where(player_1_id: p1_id, player_2_id: p2_id).one
+
+        return stats if stats
+
+        create(
+          player_1_id: p1_id,
+          player_2_id: p2_id,
+          games_played: 0,
+          wins: 0,
+          losses: 0,
+          total_elo_change: 0
+        )
+      end
+
+      def by_player(player_id)
+        partnership_stats.where(
+          Sequel.|({ player_1_id: player_id }, { player_2_id: player_id })
+        ).to_a
+      end
+
+      def update_stats(player_1_id, player_2_id, won: false, elo_change: 0)
+        stats = find_or_create(player_1_id, player_2_id)
+
+        update_params = {
+          games_played: stats.games_played + 1,
+          wins: stats.wins + (won ? 1 : 0),
+          losses: stats.losses + (won ? 0 : 1),
+          total_elo_change: stats.total_elo_change + elo_change,
+          last_played: Time.now,
+          updated_at: Time.now
+        }
+
+        update(stats.id, update_params)
+      end
+    end
+  end
+end