Fix: Implement FixPlan part A9, A10, B

src/Predictalytics.Infrastructure/Providers/Polymarket/PolymarketApiClient.cs

@@ -46,6 +46,39 @@ public class PolymarketApiClient
         return await ExecuteWithRetryAsync<List<PolymarketTradeResponse>>(_client, url, "Data", ct) ?? [];
     }
 
+    public async Task<List<PolymarketTradeResponse>> GetTradesPagedAsync(string walletAddress, int limit = 500, CancellationToken ct = default)
+    {
+        var allTrades = new List<PolymarketTradeResponse>();
+        long? endTimestamp = null;
+        
+        while (true)
+        {
+            var url = $"/activity?user={walletAddress}&limit={limit}";
+            if (endTimestamp.HasValue)
+            {
+                url += $"&end={endTimestamp.Value}";
+            }
+
+            var batch = await ExecuteWithRetryAsync<List<PolymarketTradeResponse>>(_client, url, "Data", ct);
+            if (batch == null || batch.Count == 0)
+            {
+                break;
+            }
+
+            allTrades.AddRange(batch);
+
+            if (batch.Count < limit)
+            {
+                break;
+            }
+
+            var oldestTimestamp = batch.Min(t => t.Timestamp);
+            endTimestamp = oldestTimestamp - 1;
+        }
+
+        return allTrades;
+    }
+
     public async Task<List<PolymarketTradeResponse>> GetMarketTradesAsync(string conditionId, int limit = 1000, int offset = 0, CancellationToken ct = default)
     {
         var url = $"/trades?condition_id={conditionId}&limit={limit}&offset={offset}";