fix(deploy): install libmagic in backend image

Fixes #44

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/Dockerfile

@@ -9,7 +9,7 @@ ENV PYTHONDONTWRITEBYTECODE=1 \
 WORKDIR /app
 
 RUN apt-get update \
-    && apt-get install -y --no-install-recommends curl ca-certificates \
+    && apt-get install -y --no-install-recommends curl ca-certificates libmagic1 \
     && rm -rf /var/lib/apt/lists/* \
     && pip install --no-cache-dir uv
 

backend/apps/common/tests.py

@@ -2,6 +2,7 @@ from unittest.mock import patch
 from types import SimpleNamespace
 from uuid import uuid4
 
+from django.conf import settings
 from django.test import SimpleTestCase
 from django.utils import timezone
 
@@ -35,3 +36,10 @@ class CursorPaginationTests(SimpleTestCase):
 
         self.assertEqual(decoded_created_at, created_at)
         self.assertEqual(decoded_id, str(record_id))
+
+
+class BackendImageDependencyTests(SimpleTestCase):
+    def test_backend_image_installs_libmagic_for_python_magic(self):
+        dockerfile = settings.BASE_DIR / "Dockerfile"
+
+        self.assertIn("libmagic1", dockerfile.read_text(encoding="utf-8"))