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/templates/admin/matches/index.html.erb

@@ -0,0 +1,36 @@
+<h1>Match Administration</h1>
+
+<p><a href="/admin/matches/new">Enter New Match</a> | <a href="/admin/matches/upload">Upload CSV</a></p>
+
+<% if matches.any? %>
+  <table>
+    <thead>
+      <tr>
+        <th>ID</th>
+        <th>Date</th>
+        <th>Team 1</th>
+        <th>Score</th>
+        <th>Team 2</th>
+        <th>Score</th>
+        <th>Status</th>
+      </tr>
+    </thead>
+    <tbody>
+      <% matches.each do |match| %>
+        <tr>
+          <td><%= match.id %></td>
+          <td><%= match.played_at&.strftime('%Y-%m-%d %H:%M') %></td>
+          <td><%= match.team_1_p1_id %>/<%= match.team_1_p2_id %></td>
+          <td><%= match.team_1_score %></td>
+          <td><%= match.team_2_p1_id %>/<%= match.team_2_p2_id %></td>
+          <td><%= match.team_2_score %></td>
+          <td><%= match.status %></td>
+        </tr>
+      <% end %>
+    </tbody>
+  </table>
+<% else %>
+  <p>No matches entered yet.</p>
+<% end %>
+
+<p><a href="/admin/players">Manage Players</a></p>