fix: query key consistency and timeout configuration

- Use QUERY_KEYS.sourcesInfinite for infinite scroll query key
  Starting with ['sources', ...] ensures mutations that invalidate
  ['sources'] will also invalidate the infinite scroll cache

- Use httpx.Timeout for chat service with short connect (10s) and
  long read (600s) timeouts. Prevents 10 min wait on connection errors

api/chat_service.py

@@ -135,7 +135,9 @@ class ChatService:
             if model_override is not None:
                 data["model_override"] = model_override
             
-            async with httpx.AsyncClient(timeout=600.0) as client:  # 10 min timeout for Ollama/local LLMs
+            # Short connect timeout (10s), long read timeout (10 min) for Ollama/local LLMs
+            timeout = httpx.Timeout(connect=10.0, read=600.0, write=30.0, pool=10.0)
+            async with httpx.AsyncClient(timeout=timeout) as client:
                 response = await client.post(
                     f"{self.base_url}/api/chat/execute",
                     json=data,

frontend/src/lib/api/query-client.ts

@@ -20,6 +20,7 @@ export const QUERY_KEYS = {
   notes: (notebookId?: string) => ['notes', notebookId] as const,
   note: (id: string) => ['notes', id] as const,
   sources: (notebookId?: string) => ['sources', notebookId] as const,
+  sourcesInfinite: (notebookId: string) => ['sources', 'infinite', notebookId] as const,
   source: (id: string) => ['sources', id] as const,
   settings: ['settings'] as const,
   sourceChatSessions: (sourceId: string) => ['source-chat', sourceId, 'sessions'] as const,

frontend/src/lib/hooks/use-sources.ts

@@ -31,7 +31,7 @@ export function useNotebookSources(notebookId: string) {
   const queryClient = useQueryClient()
 
   const query = useInfiniteQuery({
-    queryKey: ['notebookSources', notebookId],
+    queryKey: QUERY_KEYS.sourcesInfinite(notebookId),
     queryFn: async ({ pageParam = 0 }) => {
       const data = await sourcesApi.list({
         notebook_id: notebookId,
@@ -60,7 +60,7 @@ export function useNotebookSources(notebookId: string) {
 
   // Refetch function that resets to first page
   const refetch = useCallback(() => {
-    queryClient.invalidateQueries({ queryKey: ['notebookSources', notebookId] })
+    queryClient.invalidateQueries({ queryKey: QUERY_KEYS.sourcesInfinite(notebookId) })
   }, [queryClient, notebookId])
 
   return {