fix: session persistence, multi-turn memory, OCR pipeline, download UX (v7)

- graph.stream() state fix: agent_state now properly accumulates node updates

- atomic session save (tempfile + os.replace)

- uploaded_file_path injection for OcrExtractor + annotation_detector

- download section always visible; refreshFromApi auto-reloads after generation

- node_start/complete unfiltered for full progress visibility

- modification_request without status=='pass' check

frontend/src/App.vue

@@ -98,12 +98,12 @@ async function handleSend(text: string, files: File[]) {
         }
 
         // Refresh session sidebar data after a short delay
-        setTimeout(() => session.refreshFromState({}), 500)
+        setTimeout(() => session.refreshFromApi(), 500)
       },
       onAgentError(data) {
         chat.setError(data.error)
         chat.addMessage({ role: 'assistant', content: `执行异常: ${data.error}`, type: 'error' })
-        setTimeout(() => session.refreshFromState({}), 500)
+        setTimeout(() => session.refreshFromApi(), 500)
       },
     })
   } catch (e: any) {