chore: import upstream snapshot with attribution

app/api/qr.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+import io
+
+import segno
+from fastapi import APIRouter, HTTPException
+from fastapi.responses import Response
+
+router = APIRouter()
+
+_MAX_LEN = 500
+
+
+@router.get("/qr")
+def get_qr(url: str) -> Response:
+    if not url or len(url) > _MAX_LEN:
+        raise HTTPException(status_code=422, detail="url required (max 500 chars)")
+    qr = segno.make_qr(url, error="m")
+    buf = io.BytesIO()
+    qr.save(buf, kind="svg", scale=5, border=2, dark="#1a1206", light="#ffffff")
+    return Response(
+        content=buf.getvalue(),
+        media_type="image/svg+xml",
+        headers={"Cache-Control": "public, max-age=3600"},
+    )