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/changelog.json

@@ -1,4 +1,5 @@
 [
+  { "date": "2026-07-15", "text": "Quick actions that don't fit right now are dimmed (asleep → everything but Sleep end; awake → Sleep end) — still tappable for corrections" },
   { "date": "2026-07-15", "text": "Editing an event no longer pops the date picker over the whole screen on iPhone" },
   { "date": "2026-07-15", "text": "Weight and amount fields no longer show up on events that don't use them (e.g. editing a pee)" },
   { "date": "2026-07-15", "text": "The date in the top bar is shorter (no year), so the whole bar fits on smaller iPhones" },