Fix route diagram open issues: bugs, visual polish, interactive features

Batch 1 — Bug fixes:
- #51: Pass group+routeId to stats/timeseries API for route-scoped data
- #55: Propagate processor FAILED status to diagram error node highlighting

Batch 2 — Visual polish:
- #56: Brighter canvas background with amber/cyan radial gradients
- #57: Stronger glow filters (stdDeviation 3→6, opacity 0.4→0.6)
- #58: Uniform 200×40px leaf nodes with label truncation at 22 chars
- #59: Diagram legend (node types, edge types, overlay indicators)
- #64: SVG <title> tooltips on all nodes showing type, status, duration

Batch 3 — Interactive features:
- #60: Draggable minimap viewport (click-to-center, drag-to-pan)
- #62: CSS View Transitions slide animation, back arrow, Backspace key

Batch 4 — Advanced features:
- #50: Execution picker dropdown scoped to group+routeId
- #49: Iteration count badge (×N) on compound nodes
- #63: Route header stats (Executions Today, Success Rate, Avg, P99)

Closes #49 #50 #51 #55 #56 #57 #58 #59 #60 #62 #63 #64

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

ui/src/hooks/useExecutionOverlay.ts

@@ -13,6 +13,7 @@ export interface OverlayState {
   executedEdges: Set<string>;
   durations: Map<string, number>;
   sequences: Map<string, number>;
+  statuses: Map<string, string>;
   iterationData: Map<string, IterationData>;
   selectedNodeId: string | null;
   selectNode: (nodeId: string | null) => void;
@@ -25,6 +26,7 @@ function collectProcessorData(
   executedNodes: Set<string>,
   durations: Map<string, number>,
   sequences: Map<string, number>,
+  statuses: Map<string, string>,
   counter: { seq: number },
 ) {
   for (const proc of processors) {
@@ -33,9 +35,10 @@ function collectProcessorData(
       executedNodes.add(nodeId);
       durations.set(nodeId, proc.durationMs ?? 0);
       sequences.set(nodeId, ++counter.seq);
+      if (proc.status) statuses.set(nodeId, proc.status);
     }
     if (proc.children && proc.children.length > 0) {
-      collectProcessorData(proc.children, executedNodes, durations, sequences, counter);
+      collectProcessorData(proc.children, executedNodes, durations, sequences, statuses, counter);
     }
   }
 }
@@ -68,19 +71,20 @@ export function useExecutionOverlay(
     if (execution) setIsActive(true);
   }, [execution]);
 
-  const { executedNodes, durations, sequences, iterationData } = useMemo(() => {
+  const { executedNodes, durations, sequences, statuses, iterationData } = useMemo(() => {
     const en = new Set<string>();
     const dur = new Map<string, number>();
     const seq = new Map<string, number>();
+    const st = new Map<string, string>();
     const iter = new Map<string, IterationData>();
 
     if (!execution?.processors) {
-      return { executedNodes: en, durations: dur, sequences: seq, iterationData: iter };
+      return { executedNodes: en, durations: dur, sequences: seq, statuses: st, iterationData: iter };
     }
 
-    collectProcessorData(execution.processors, en, dur, seq, { seq: 0 });
+    collectProcessorData(execution.processors, en, dur, seq, st, { seq: 0 });
 
-    return { executedNodes: en, durations: dur, sequences: seq, iterationData: iter };
+    return { executedNodes: en, durations: dur, sequences: seq, statuses: st, iterationData: iter };
   }, [execution]);
 
   const executedEdges = useMemo(
@@ -119,6 +123,7 @@ export function useExecutionOverlay(
     executedEdges,
     durations,
     sequences,
+    statuses,
     iterationData: new Map([...iterationData].map(([k, v]) => {
       const current = iterations.get(k) ?? v.current;
       return [k, { ...v, current }];