search: compose ORDER BY with execution_id when afterExecutionId set

Follow-up to Task 1.2 flagged by Task 1.5 review (I-1). Single-column
ORDER BY could drop tail rows in a same-millisecond group >50 when
paginating via the composite cursor. Appending ', execution_id <dir>'
as secondary key only when afterExecutionId is set preserves existing
behaviour for UI/stats callers.

cameleer-server-app/src/main/java/com/cameleer/server/app/search/ClickHouseSearchIndex.java

@@ -81,13 +81,24 @@ public class ClickHouseSearchIndex implements SearchIndex {
             String sortColumn = SORT_FIELD_MAP.getOrDefault(request.sortField(), "start_time");
             String sortDir = "asc".equalsIgnoreCase(request.sortDir()) ? "ASC" : "DESC";
 
+            // Composite-cursor callers (afterExecutionId set) need a deterministic tiebreak inside
+            // same-millisecond groups so the client-side last-row pick matches ClickHouse's row order.
+            // Without this, a same-start_time tail >LIMIT can silently drop rows: the page ends mid-ms,
+            // the cursor advances past the returned lastRowId, and the skipped rows with smaller
+            // execution_id values never reappear. Other callers (UI/stats) keep the unchanged
+            // single-column ORDER BY — they don't use the composite cursor.
+            String orderBy = sortColumn + " " + sortDir;
+            if (request.afterExecutionId() != null) {
+                orderBy += ", execution_id " + sortDir;
+            }
+
             String dataSql = "SELECT execution_id, route_id, instance_id, application_id, "
                     + "status, start_time, end_time, duration_ms, correlation_id, "
                     + "error_message, error_stacktrace, diagram_content_hash, attributes, "
                     + "has_trace_data, is_replay, "
                     + "input_body, output_body, input_headers, output_headers, root_cause_message "
                     + "FROM executions FINAL WHERE " + whereClause
-                    + " ORDER BY " + sortColumn + " " + sortDir
+                    + " ORDER BY " + orderBy
                     + " LIMIT ? OFFSET ?";
 
             List<Object> dataParams = new ArrayList<>(params);