Show params column in log grid

Exposes the stored params (e.g. date_from/date_to for baseline/reference)
so the date range used in each operation is visible in the log.

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

public/app.js

@@ -822,6 +822,8 @@ function renderLogGrid(logs) {
         { field: 'operation', headerName: 'Operation',  width: 90 },
         { field: 'slice',     headerName: 'Slice',      flex: 1,
           valueFormatter: p => p.value ? JSON.stringify(p.value) : '' },
+        { field: 'params',    headerName: 'Params',     flex: 1,
+          valueFormatter: p => p.value ? JSON.stringify(p.value) : '' },
         { field: 'note',      headerName: 'Note',       flex: 1 },
         {
             headerName: '',