Fix shell details: distro name, storage path only in footer

- OS name comes from /etc/os-release (e.g. 'CachyOS Linux'), mirroring
  the original app's os_utils; macOS/Windows get proper names too
- Status pill shows the name as-is instead of uppercasing it
- Removed the watched-folder path next to the logo; it now appears only
  in the footer strip (spec updated to match)

backend/apps/core/views.py

@@ -1,4 +1,3 @@
-import platform
 import time
 
 from django.conf import settings
@@ -6,13 +5,7 @@ from rest_framework.permissions import AllowAny
 from rest_framework.response import Response
 from rest_framework.views import APIView
 
-
-def _os_info():
-    system = platform.system()
-    icon = {"Linux": "linux", "Darwin": "apple", "Windows": "windows"}.get(
-        system, "unknown"
-    )
-    return {"name": system, "release": platform.release(), "icon": icon}
+from .system_info import get_os_info
 
 
 def _worker_counts():
@@ -35,7 +28,7 @@ class StatusView(APIView):
             "env": settings.APP_ENV,
             "git_hash": settings.GIT_COMMIT_HASH,
             "version": settings.APP_VERSION,
-            "os": _os_info(),
+            "os": get_os_info(),
             "watched_folder": settings.WATCHED_FOLDER,
             "e621_time_ms": None,  # no e621 calls in the backend yet
             "workers": _worker_counts(),