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/templates/admin/tournaments/results.html.erb

@@ -0,0 +1,44 @@
+<h1>Enter Results: <%= tournament.name %> - Round <%= round[:round_number] %></h1>
+
+<form action="/admin/tournaments/<%= tournament.id %>/results" method="post">
+  <input type="hidden" name="_csrf_token" value="<%= csrf_token %>">
+
+  <table>
+    <thead>
+      <tr>
+        <th>Matchup</th>
+        <th>Team 1</th>
+        <th>Score</th>
+        <th>vs</th>
+        <th>Team 2</th>
+        <th>Score</th>
+      </tr>
+    </thead>
+    <tbody>
+      <% matchups.each_with_index do |matchup, i| %>
+        <% team_1 = teams.find { |t| t.id == matchup[:team_1_id] } %>
+        <% team_2 = teams.find { |t| t.id == matchup[:team_2_id] } %>
+        <% next if team_1.nil? || team_2.nil? %>
+        <tr>
+          <td><%= i + 1 %></td>
+          <td><%= team_1.team_name %></td>
+          <td>
+            <input type="number" name="team_1_score_<%= matchup[:id] %>" min="0" max="10" value="10" style="width: 60px;">
+          </td>
+          <td>vs</td>
+          <td><%= team_2.team_name %></td>
+          <td>
+            <input type="number" name="team_2_score_<%= matchup[:id] %>" min="0" max="10" value="7" style="width: 60px;">
+          </td>
+          <td>
+            <input type="checkbox" name="matchup_<%= matchup[:id] %>" checked style="display:none;">
+          </td>
+        </tr>
+      <% end %>
+    </tbody>
+  </table>
+
+  <button type="submit">Save All Results</button>
+</form>
+
+<p><a href="/admin/tournaments/<%= tournament.id %>">Back to Tournament</a></p>