test(timeline): pin the medication rows, the open day, the point card and the page height

The journey now writes two medications through the real routes (one with
a start date and its course, one known only by an intake) and asserts
each is drawn on exactly one row; carries an open day from /timeline to
/labs and back after folding it; hovers and focuses a value point and
checks the card names that line alone and stays inside the chart; and
measures the page at 1280, 1440 and 1920 px, with and without the docked
day: no sideways scroll, and no height past the content beyond the
shell's own padding. Expanding all of a day's values scrolls the panel
and leaves the page height as it was. The "Open <day>" link the bar no
longer has is asserted absent; a chip opens the day instead.

Label texts carry their lane under their own attribute, so a lane
selector matches the lane and not its names.

src/components/timeline/timeline-chart.tsx

@@ -582,8 +582,8 @@ function ChartBody({
           lane.labels.map((label, i) => (
             <text
               key={`label-${lane.key}-${label.itemId}-${i}`}
-              data-lane={lane.key}
-              data-item={label.itemId}
+              data-label-lane={lane.key}
+              data-label-item={label.itemId}
               x={label.x}
               y={label.y}
               fontSize={11}