fix: ENDPOINT node execution state, badge position, and edge traversal

- Synthesize COMPLETED state for ENDPOINT nodes when overlay is active
  (endpoints are route entry points, not in the processor execution tree)
- Move status badge (check/error) inside the card (top-right, below top bar)
  to avoid collision with ConfigBadge (TRACE/TAP) badges
- Include ENDPOINT nodes in edge traversal check so the edge from
  endpoint to first processor renders as green/traversed

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/ProcessDiagram/DiagramNode.tsx

@@ -129,16 +129,16 @@ export function DiagramNode({
       {/* Config badges */}
       {config && <ConfigBadge nodeWidth={w} config={config} />}
 
-      {/* Execution overlay: status badge at top-right */}
+      {/* Execution overlay: status badge inside card, top-right corner */}
       {isCompleted && (
         <>
-          <circle cx={w - 8} cy={-8} r={8} fill="#3D7C47" />
+          <circle cx={w - 10} cy={TOP_BAR_HEIGHT + 8} r={6} fill="#3D7C47" />
           <text
-            x={w - 8}
-            y={-4}
+            x={w - 10}
+            y={TOP_BAR_HEIGHT + 11}
             textAnchor="middle"
             fill="white"
-            fontSize={11}
+            fontSize={9}
             fontWeight={700}
           >
             &#x2713;
@@ -147,13 +147,13 @@ export function DiagramNode({
       )}
       {isFailed && (
         <>
-          <circle cx={w - 8} cy={-8} r={8} fill="#C0392B" />
+          <circle cx={w - 10} cy={TOP_BAR_HEIGHT + 8} r={6} fill="#C0392B" />
           <text
-            x={w - 8}
-            y={-4}
+            x={w - 10}
+            y={TOP_BAR_HEIGHT + 11}
             textAnchor="middle"
             fill="white"
-            fontSize={12}
+            fontSize={9}
             fontWeight={700}
           >
             !