The status bar draws a notification's small icon from its alpha channel
alone, so the silhouette is all that distinguishes an app there — and ours
was the stock Material "event" glyph, the same shape the system's date
surfaces and every other calendar app use.
Redrawn at 24dp from the launcher mark: calendar body plus the bloom badge,
numeral dropped and the petals filled rather than stroked, both of which
turn to mush at this size. The shade needs no change — since Android 12 its
header shows the launcher icon, which is already unmistakable.
