fix: comprehensive QA — resolve 13 bugs, add UX improvements across all services

Client SDK: add .catch() to graphRagStreaming/documentRagStreaming (silent timeout),
null-guard JSON.parse in getPrompts/getSystemPrompt/getPrompt.

Backend: implement "getvalues" config operation for token costs, null-check
createTerm() in FalkorDB triples query, add knowledge-cores service entrypoint
and Docker entry, return proper HTTP 400/404 for gateway error responses.

Workbench: cancel button + elapsed timer for chat, clear agent spinner on error,
flow dialog inline validation, responsive header wrapping, knowledge cores
loading timeout, sidebar/page naming consistency, theme toggle indicator.

Infrastructure: enable Grafana Explore for viewers, add gateway Prometheus
scrape target, fix RAG pipeline dashboard layout (6 panels visible),
filter Service Health to configured targets only.

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

ts/packages/workbench/src/providers/socket-provider.tsx

@@ -1,5 +1,6 @@
 import {
   createContext,
+  useCallback,
   useContext,
   useEffect,
   useRef,
@@ -112,14 +113,20 @@ export function useConnectionState(): ConnectionState {
     hasApiKey: false,
   });
 
-  const subscribe = (onStoreChange: () => void) => {
-    return api.onConnectionStateChange((next) => {
-      stateRef.current = next;
-      onStoreChange();
-    });
-  };
+  // subscribe must be stable across renders to prevent useSyncExternalStore
+  // from re-subscribing on every render (which would cause an infinite loop
+  // because onConnectionStateChange immediately calls the listener).
+  const subscribe = useCallback(
+    (onStoreChange: () => void) => {
+      return api.onConnectionStateChange((next) => {
+        stateRef.current = next;
+        onStoreChange();
+      });
+    },
+    [api],
+  );
 
-  const getSnapshot = () => stateRef.current;
+  const getSnapshot = useCallback(() => stateRef.current, []);
 
   return useSyncExternalStore(subscribe, getSnapshot, getSnapshot);
 }