chore: normalize line endings (CRLF -> LF)

No content changes: git diff --ignore-all-space over these files is empty.
The churn came from editing on Windows against a repo checked out with LF.

backend/.gitignore

@@ -1,18 +1,18 @@
-.venv/
-.venv-api/
-.env
-__pycache__/
-*.pyc
-.python-version
-.antigravitycli/
-PaddleOCR-VL-1.6_Online_Demo/examples/do-pfm/*.jpg
-pfm-web-app/public/do-pfm/*
-uploads/*
-pfm-web-app/public/produk-pfm/**/*.jpeg
-pfm-web-app/public/produk-pfm/yolo_dataset/*
-pfm-web-app/public/produk-pfm/runs/*
-pfm-web-app/public/produk-pfm/models/*
-*.pt
-test_img.jpeg
-screenshots/*.jpg
-pfm-web-app/public/test-images/*
+.venv/
+.venv-api/
+.env
+__pycache__/
+*.pyc
+.python-version
+.antigravitycli/
+PaddleOCR-VL-1.6_Online_Demo/examples/do-pfm/*.jpg
+pfm-web-app/public/do-pfm/*
+uploads/*
+pfm-web-app/public/produk-pfm/**/*.jpeg
+pfm-web-app/public/produk-pfm/yolo_dataset/*
+pfm-web-app/public/produk-pfm/runs/*
+pfm-web-app/public/produk-pfm/models/*
+*.pt
+test_img.jpeg
+screenshots/*.jpg
+pfm-web-app/public/test-images/*