Fix scale-selection 500 error (missing BytesIO import) and compact GPU badge

ai_tools.py: add 'from io import BytesIO' — scale_selection and paste
endpoints used BytesIO directly but it was only imported locally in one
unrelated function, causing NameError on every scale call.

provider-badge.js: redesign badge to fit the narrow (~40px) left toolbar.
Was rendering 'GPU · sdxl_offload · Quadro RTX 3000' inline which wrapped
into multiple lines covering tool icons. Now shows a status dot + short
label (SDXL / OAI / Rep…) with all details moved to the hover tooltip.

https://claude.ai/code/session_01WVDg7amsy1TTtxvpku7bcM

backend/app/routers/ai_tools.py

@@ -10,6 +10,7 @@ from typing import Optional
 import base64
 import asyncio
 import json
+from io import BytesIO
 
 from app.services.local_inpaint import (
     lama_inpaint, opencv_inpaint, lama_available, gpu_available, rembg_available,