Fix async file read bug causing 'coroutine object is not subscriptable'

FastAPI UploadFile.read() is async and returns a coroutine. The sync
ingest_file() was receiving the coroutine instead of bytes. Now we
await the read in the async endpoint and wrap the content in BytesIO.

Co-authored-by: Cursor <cursoragent@cursor.com>

api.py

@@ -14,6 +14,7 @@ from fastapi.middleware.cors import CORSMiddleware
 from pydantic import BaseModel
 from typing import List
 import os
+import io
 
 app = FastAPI(title="DocMind AI API", version="3.0")
 
@@ -133,8 +134,12 @@ async def upload_document(file: UploadFile = File(...)):
         )
 
     try:
-        rag    = get_rag()
-        chunks = rag.ingest_file(file)
+        rag     = get_rag()
+        content = await file.read()
+        buf     = io.BytesIO(content)
+        buf.name     = filename
+        buf.filename = filename
+        chunks  = rag.ingest_file(buf)
 
         type_labels = {
             ".pdf": "PDF Document",