fix: show CLS metric when value is 0#4797
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When Chrome's Layout Instability API observer never fires (no layout shifts on the page), cumulativeLayoutShift stays undefined. The aggregator skipped it entirely, so no stats were generated and the template never rendered the CLS section. Fix: default to 0 in the aggregator when pageinfo exists but CLS is undefined, and relax the template guards so they render for any pageinfo (not just when CLS !== undefined). Fixes sitespeedio#4547
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Description
When Chrome's Layout Instability API observer never fires (no layout shifts on the page), \cumulativeLayoutShift\ stays \undefined. The aggregator skipped it entirely, so no stats were generated and the template never rendered the CLS section — making it look like the metric was missing.
Root cause
In \�rowsertimeAggregator.js, the guard !== undefined\ prevented pushing a 0 value when the observer never fired. The Pug templates had matching guards that hid the entire CLS section.
Fix