fix(profile): dispose stale ECharts instance in initEChart - #29

Problem

On the profile page, switching from one person to another left the Contributions Over Time chart showing the previous person's series. For example, going to Anjo Vahldiek-Oberwagner (who has AE Committee Service) and then changing the name to Christian Rossow showed the same early "AE Committee Service" bars that belonged to Anjo.

Root cause

echarts.init(el) returns the existing instance already attached to a DOM node rather than a fresh one. The profile page re-calls initEChart on the same #timelineChart element on every profile switch, and renderContributionChart then calls setOption(...) with the default merge semantics. ECharts merges series by index, so when the new person has fewer series (e.g. only "Artifact Papers"), the previous person's higher-index series ("ArtiFinder (discovered)", "AE Committee Service") are never removed.

Fix

Dispose any pre-existing ECharts instance on the element inside initEChart before creating a new one, so every re-render starts from a clean slate. Because the fix is centralized in initEChart, it also resolves the same latent staleness for any other chart that re-renders on the same element (e.g. the ranking-history chart), and it preserves theming since the fresh instance re-applies the light/dark baseline. The wrapped dispose also disconnects the ResizeObserver, so there is no observer leak.

   R.initEChart = function(el) {
     if (typeof el === 'string') el = document.getElementById(el);
     if (!el) return null;
+    var existing = echarts.getInstanceByDom(el);
+    if (existing) existing.dispose();
     var chart = echarts.init(el, null, { renderer: 'canvas' });

Testing

• Verified the data itself is correct (Adam Belay / others), so this was purely a client-side rendering-state bug.
• After the change, switching profiles renders only the current person's series.