Lift the chart window out of the Sleep panel

It governs nearly every panel on the page — the training grid, the timing
charts, both sleep patterns, the counts panel, all three walk views — but it
sat inside Sleep, so it read as a sleep setting. That was already the reason
its old home carried a comment explaining it was not one; a control needing a
comment to deny what its position says is in the wrong position.

It now has its own row under the quick actions, above the first panel that
reads it, with a "Charts cover" label to say what it does. The row skips the
card chrome: it is a control, not content, and giving it a section's surface
and shadow would have made it look like a panel with nothing in it.

No JS change — both the click wiring and renderChartWindow address the buttons
by class, so they never cared where the picker lived.

Also removes that old comment, which had stopped being wrong about the picker
and started being wrong about the panel: the walks move carried it along by
accident and left it sitting above Weight, explaining a control three panels
away.

src/changelog.json

@@ -1,4 +1,5 @@
 [
+  { "date": "2026-09-01", "text": "The 7d / 14d / 30d buttons have moved out of the Sleep panel onto their own “Charts cover” row, just under the Log event buttons. They always set the window for every chart on the page — training, timing, sleep, walks, pees/poos/meals — but sitting inside the Sleep panel made them look like a sleep setting" },
   { "date": "2026-09-01", "text": "Dropped the “Darker = more sessions that day” caption under the training consistency grid. Tapping a cell still opens that day" },
   { "date": "2026-09-01", "text": "Dropped two hint lines: the “Based on N pee gaps…” sentence under the Timing charts, and the “Rule of thumb at this age…” one in the Walks panel. The charts above them already say it. The age-based walking goal is still there, drawn as the goal line on the Walk trend" },
   { "date": "2026-09-01", "text": "On the dark theme the awake timers are a warm near-white now — both “Awake for” at the top and the pill in the day bar — instead of yellow text on a yellow-tinted pill. The light theme keeps its dark gold, where white would disappear into a near-white pill" },