Rule preview should show error message when time series data has non-ascending timestamps

### Problem When creating alert rules with data that has timestamps in non-ascending order, the Alerting UI silently fails to display the data properly. Instead of showing an error message, it: - Renders a table view instead of the expected time series visualization - Shows generic "Series 1", "Series 2" labels instead of actual field names - Provides no indication to users about what's wrong ### Root Cause The `isTimeSeriesFrame()` function in `@grafana/data` requires timestamps to be in ascending order. When this check fails, it returns `false` without providing any error context. The UI components (`VizWrapper.tsx`, `Expression.tsx`) then silently fall back to table rendering. ### Expected Behavior When time series data is detected but timestamps are not in ascending order, show a clear error message: > "Time series data must have timestamps in ascending order. Please sort your query results by time in ascending order." ### Impact - Users are confused when queries work in panels but fail in alerting - No way to diagnose the issue without deep investigation ### Relevant Code Locations - `packages/grafana-data/src/dataframe/utils.ts` - `isTimeSeriesField()` (lines 43-66) - `public/app/features/alerting/unified/components/rule-editor/VizWrapper.tsx` (line 23) - `public/app/features/alerting/unified/components/expressions/Expression.tsx` (line 219) ### Related Issues - Support escalation: grafana/support-escalations#18479