Server-side sorting for execution search results

Sorting now applies to the entire result set via ClickHouse ORDER BY
instead of only sorting the current page client-side. Default sort
order is timestamp descending. Supported sort columns: startTime,
status, agentId, routeId, correlationId, durationMs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/search/ClickHouseSearchEngine.java

@@ -51,10 +51,11 @@ public class ClickHouseSearchEngine implements SearchEngine {
         // Data query
         params.add(request.limit());
         params.add(request.offset());
+        String orderDir = "asc".equalsIgnoreCase(request.sortDir()) ? "ASC" : "DESC";
         String dataSql = "SELECT execution_id, route_id, agent_id, status, start_time, end_time, " +
                 "duration_ms, correlation_id, error_message, diagram_content_hash " +
                 "FROM route_executions" + where +
-                " ORDER BY start_time DESC LIMIT ? OFFSET ?";
+                " ORDER BY " + request.sortColumn() + " " + orderDir + " LIMIT ? OFFSET ?";
 
         List<ExecutionSummary> data = jdbcTemplate.query(dataSql, (rs, rowNum) -> {
             Timestamp endTs = rs.getTimestamp("end_time");