feat: use endpointUri for cross-route drill-down instead of label parsing

Server:
- Add endpointUri to PositionedNode (from RouteNode)
- Add fromEndpointUri to RouteSummary (catalog API)
- Catalog controller resolves endpoint URI from diagram store

UI:
- Build endpointRouteMap from catalog's fromEndpointUri field
- Drill-down uses exact match on node.endpointUri against the map
- Remove label parsing heuristics (extractTargetEndpoint, camelToKebab)

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

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/RouteCatalogController.java

@@ -3,9 +3,11 @@ package com.cameleer3.server.app.controller;
 import com.cameleer3.server.app.dto.AgentSummary;
 import com.cameleer3.server.app.dto.AppCatalogEntry;
 import com.cameleer3.server.app.dto.RouteSummary;
+import com.cameleer3.common.graph.RouteGraph;
 import com.cameleer3.server.core.agent.AgentInfo;
 import com.cameleer3.server.core.agent.AgentRegistryService;
 import com.cameleer3.server.core.agent.AgentState;
+import com.cameleer3.server.core.storage.DiagramStore;
 import com.cameleer3.server.core.storage.StatsStore;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
@@ -34,10 +36,14 @@ import java.util.stream.Collectors;
 public class RouteCatalogController {
 
     private final AgentRegistryService registryService;
+    private final DiagramStore diagramStore;
     private final JdbcTemplate jdbc;
 
-    public RouteCatalogController(AgentRegistryService registryService, JdbcTemplate jdbc) {
+    public RouteCatalogController(AgentRegistryService registryService,
+                                   DiagramStore diagramStore,
+                                   JdbcTemplate jdbc) {
         this.registryService = registryService;
+        this.diagramStore = diagramStore;
         this.jdbc = jdbc;
     }
 
@@ -114,12 +120,14 @@ public class RouteCatalogController {
 
             // Routes
             Set<String> routeIds = routesByApp.getOrDefault(appId, Set.of());
+            List<String> agentIds = agents.stream().map(AgentInfo::id).toList();
             List<RouteSummary> routeSummaries = routeIds.stream()
                     .map(routeId -> {
                         String key = appId + "/" + routeId;
                         long count = routeExchangeCounts.getOrDefault(key, 0L);
                         Instant lastSeen = routeLastSeen.get(key);
-                        return new RouteSummary(routeId, count, lastSeen);
+                        String fromUri = resolveFromEndpointUri(routeId, agentIds);
+                        return new RouteSummary(routeId, count, lastSeen, fromUri);
                     })
                     .toList();
 
@@ -141,6 +149,15 @@ public class RouteCatalogController {
         return ResponseEntity.ok(catalog);
     }
 
+    /** Resolve the from() endpoint URI for a route by looking up its diagram. */
+    private String resolveFromEndpointUri(String routeId, List<String> agentIds) {
+        return diagramStore.findContentHashForRouteByAgents(routeId, agentIds)
+                .flatMap(diagramStore::findByContentHash)
+                .map(RouteGraph::getRoot)
+                .map(root -> root.getEndpointUri())
+                .orElse(null);
+    }
+
     private String computeWorstHealth(List<AgentInfo> agents) {
         boolean hasDead = false;
         boolean hasStale = false;