Overlay app favicon.ico from the Periscope mark.

Replaces the leftover OSS Next.ico so /favicon.ico matches favicon_io.

tests/test_periscope_favicon_overlay.py

@@ -0,0 +1,17 @@
+"""App favicon overlay is the Periscope mark, not the leftover OSS ico."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+SRC = ROOT / "periscope" / "src" / "frontend"
+
+
+def test_app_favicon_is_src_periscope_mark():
+    overlay = SRC / "src" / "app" / "favicon.ico"
+    mark = SRC / "public" / "favicon_io" / "favicon.ico"
+    assert overlay.is_file()
+    assert mark.is_file()
+    assert overlay.stat().st_size == mark.stat().st_size
+    assert overlay.read_bytes() == mark.read_bytes()