Fix hover flicker on Runs by status chart

Moving the mouse across the stacked bar chart caused the bars to strobe
between bright and dim. Each <Bar> had an onMouseLeave that reset the
highlight state, so crossing from one series to the next fired
leave (activeBarKey → null, all bars bright) before the next bar's enter
(activeBarKey → new key, others dim). That null→key churn produced the
flicker.

Remove the per-Bar onMouseLeave. Moving between bars now only updates the
active key via onMouseEnter, and the existing chart-level onMouseLeave
(handleMouseLeave, which calls highlight.reset) still clears the highlight
when the cursor leaves the whole chart. Legend hover is unaffected — it
uses its own onMouseEnter/onMouseLeave handlers.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018wP95TbXaujzKBnDJbCD7u

apps/webapp/app/components/primitives/charts/ChartBar.tsx

@@ -320,7 +320,10 @@ export function ChartBarRenderer({
                 highlight.setHoveredBar(hoveredKey, index);
               }
             }}
-            onMouseLeave={highlight.reset}
+            // No per-Bar onMouseLeave: moving between bars would fire leave→reset
+            // (all bars snap bright) before the next bar's enter, causing a hover
+            // flicker. The chart-level onMouseLeave (handleMouseLeave) clears the
+            // highlight when the cursor exits the whole chart.
             isAnimationActive={false}
           />
         );