Dim quick actions that don't fit the current sleep state

Asleep: everything but Sleep end fades; awake: only Sleep end fades; no
sleep history: nothing. Buttons stay clickable — it's a visual nudge for
the thumb, not a lockout, so corrections still work.

src/style.css

@@ -255,6 +255,9 @@ button.action.eat   { background: var(--eat); }
 button.action.pee   { background: var(--pee); color: #2b240a; }
 button.action.poo   { background: var(--poo); }
 button.action.weight { background: var(--weight); }
+/* Unlikely given the current sleep state (see renderActionHints) — dimmed
+   but fully tappable, so corrections are never blocked. */
+button.action.unlikely { opacity: 0.4; }
 
 button.ghost {
   background: transparent;