Home-screen icon: the piper replaces iOS's letter tile

iOS asks for apple-touch-icon when saving to the home screen and we
served nothing — hence the gray "B". A 180x180 PNG cropped from the
mascot logo is linked from the shell, served from /static/, and also
answers the cookie-less root probes (/apple-touch-icon*.png) the guard
already treats as public. apple-mobile-web-app-title trims the clip
name to "bggpipe".

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jXZFSTZQKzAC8fqpWSz9g

tests/test_webreview.py

@@ -1048,3 +1048,14 @@ def test_lan_403_is_html_for_navigations(tmp_path):
     res = phone.get("/titles", headers={"accept": "text/html,application/xhtml+xml"})
     assert res.status_code == 403
     assert "access key needed" in res.text  # a person sees prose, not JSON
+
+
+def test_home_screen_icon_is_served_and_public(tmp_path):
+    cfg = make_cfg(tmp_path)
+    app = create_app(cfg, client=unauthorized_client(tmp_path), lan_token="sekret")
+    phone = TestClient(app, base_url="http://192.168.1.99:8377")
+    # iOS probes cookie-less; both the root probe and the linked path work
+    assert phone.get("/apple-touch-icon.png").status_code == 200
+    assert phone.get("/static/apple-touch-icon.png").status_code == 200
+    page = phone.get("/?k=sekret", follow_redirects=True)
+    assert 'rel="apple-touch-icon"' in page.text