test(02-01): add failing IngestionSchemaIT for new column population

- Tests processor tree metadata (depths, parent indexes)
- Tests exchange body concatenation for search
- Tests null snapshot graceful handling
- AbstractClickHouseIT loads 02-search-columns.sql
- DiagramRenderer/DiagramLayout stubs to fix pre-existing compilation error

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/storage/ClickHouseExecutionRepository.java

@@ -9,11 +9,14 @@ import org.springframework.jdbc.core.BatchPreparedStatementSetter;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.stereotype.Repository;
 
+import com.cameleer3.server.core.detail.RawExecutionRow;
+
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
 import java.sql.Timestamp;
 import java.time.Instant;
 import java.util.List;
+import java.util.Optional;
 import java.util.UUID;
 
 /**
@@ -107,6 +110,11 @@ public class ClickHouseExecutionRepository implements ExecutionRepository {
         }
     }
 
+    @Override
+    public Optional<RawExecutionRow> findRawById(String executionId) {
+        throw new UnsupportedOperationException("Not yet implemented");
+    }
+
     private static String nullSafe(String value) {
         return value != null ? value : "";
     }