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/api/queries/executions.ts

@@ -2,15 +2,22 @@ import { useQuery } from '@tanstack/react-query';
 import { api } from '../client';
 import type { SearchRequest } from '../types';
 
-export function useExecutionStats(timeFrom: string | undefined, timeTo: string | undefined) {
+export function useExecutionStats(
+  timeFrom: string | undefined,
+  timeTo: string | undefined,
+  routeId?: string,
+  group?: string,
+) {
   return useQuery({
-    queryKey: ['executions', 'stats', timeFrom, timeTo],
+    queryKey: ['executions', 'stats', timeFrom, timeTo, routeId, group],
     queryFn: async () => {
       const { data, error } = await api.GET('/search/stats', {
         params: {
           query: {
             from: timeFrom!,
             to: timeTo || undefined,
+            routeId: routeId || undefined,
+            group: group || undefined,
           },
         },
       });
@@ -38,9 +45,14 @@ export function useSearchExecutions(filters: SearchRequest, live = false) {
   });
 }
 
-export function useStatsTimeseries(timeFrom: string | undefined, timeTo: string | undefined) {
+export function useStatsTimeseries(
+  timeFrom: string | undefined,
+  timeTo: string | undefined,
+  routeId?: string,
+  group?: string,
+) {
   return useQuery({
-    queryKey: ['executions', 'timeseries', timeFrom, timeTo],
+    queryKey: ['executions', 'timeseries', timeFrom, timeTo, routeId, group],
     queryFn: async () => {
       const { data, error } = await api.GET('/search/stats/timeseries', {
         params: {
@@ -48,6 +60,8 @@ export function useStatsTimeseries(timeFrom: string | undefined, timeTo: string
             from: timeFrom!,
             to: timeTo || undefined,
             buckets: 24,
+            routeId: routeId || undefined,
+            group: group || undefined,
           },
         },
       });