fix(labs): keep the value and draw-date column inside the dialog body

The single-column grid used the implicit auto track, which grows to the
widest cell's min-content. The draw date's date and time inputs size
from the font, so with wider metrics that min-content passed the dialog
body (about 422 px against 398 px) and the value input ran 24 px into
the dialog's padding. An explicit grid-cols-1 track is minmax(0, 1fr)
and stays at the body's width; the date row already shrinks inside it.

Refs #1214

src/components/labs/lab-form.tsx

@@ -452,8 +452,12 @@ export function LabForm({
             column halved the draw date's cell, and `DateTimeField` sets its
             date and time halves side by side from `sm:` up, so the date
             itself was squeezed until it could only be set through the
-            calendar (#1214). */}
-        <div className="grid gap-4">
+            calendar (#1214). The column is `grid-cols-1`, not the implicit
+            `auto` column: an `auto` track grows to the widest cell's
+            min-content, and the date and time inputs' intrinsic widths
+            follow the font, so with wider metrics the track outgrew the
+            dialog body and the value input ran into its padding. */}
+        <div className="grid grid-cols-1 gap-4">
           <div className="space-y-1.5">
             {resultType === "numeric" ? (
               <>