style(insights): trends-row equal-height + mood-chart gridline density parity

Two coupled fixes pinned by Marc on the v1.4.25 W3 walkthrough:

1. Trends row equal-height
   The three trend cards (BP / Weight / Mood) on /insights sit in a
   `grid-cols-1 md:grid-cols-3` grid. The `min-h-[300px]` floor
   guarantees a sensible mobile height, but the AI annotation prose
   varies card-to-card on desktop, leaving the tallest card pushing
   only its own row member down — siblings stayed short. Added
   `md:auto-rows-fr md:items-stretch` on the grid container and
   `h-full` on each direct child so the row pins every card to the
   tallest member's height.

2. Mood chart gridline density parity
   The mood chart's YAxis pins ticks to [1,2,3,4,5] (mood scale). By
   default Recharts syncs CartesianGrid coordinates with YAxis ticks,
   so the mini variant painted five horizontal lines while the
   BP/Weight/Pulse minis painted six (their auto-generated YAxis
   ticks land on ~six bands in typical health ranges). Added a
   `horizontalCoordinatesGenerator` that emits six evenly-spaced
   lines inside the plot area so the trends row reads as a single
   rhythm.

Both changes are presentational — no chart data shape changes, no
behaviour changes, no API touched.

src/components/charts/mood-chart.tsx

@@ -621,10 +621,32 @@ export function MoodChart({
                 data={chartDataWithCompare ?? chartData}
                 margin={{ top: 10, right: 8, bottom: 8, left: 8 }}
               >
+                {/* v1.4.25 W3 — the mood chart's YAxis is pinned to
+                    five mood-score ticks ([1,2,3,4,5]), which Recharts
+                    syncs with CartesianGrid by default. That left the
+                    mini variant painting five horizontal lines while
+                    the BP / Weight / Pulse minis painted six (their
+                    auto-generated YAxis ticks land on six bands in
+                    typical health ranges). The explicit coordinates
+                    generator below produces six evenly-spaced lines
+                    so the trends row reads as a single rhythm. */}
                 <CartesianGrid
                   strokeDasharray="3 3"
                   stroke="hsl(var(--border))"
                   opacity={0.5}
+                  horizontalCoordinatesGenerator={({ offset }) => {
+                    // `offset` carries the chart's plot-area metrics.
+                    // Six evenly-spaced y-coordinates inside the plot
+                    // area (top + 4 intermediate + bottom) match the
+                    // density of the BP/Weight/Pulse minis.
+                    const top = offset.top ?? 0;
+                    const height = offset.height ?? 0;
+                    if (height <= 0) return [];
+                    const lines = 6;
+                    return Array.from({ length: lines }, (_, i) =>
+                      Math.round(top + (height * i) / (lines - 1)),
+                    );
+                  }}
                 />
                 {showBands &&
                   VALUE_BANDS.map((band) => (

src/components/insights/trends-row.tsx

@@ -98,13 +98,17 @@ export function TrendsRow({ annotations, confidence }: TrendsRowProps) {
           three cards on visibly different baselines. Each card is now
           a flex column with `min-h-[300px]` so the chart anchors to
           the top and the annotation grows downward into a shared
-          minimum height. The grid + min-h together preserve the visual
-          rhythm even on a row where only one annotation is multi-line. */}
-      <div className="grid grid-cols-1 gap-4 md:grid-cols-3">
+          minimum height.
+          v1.4.25 W3 — strengthen the equal-height contract with
+          `md:auto-rows-fr` + `md:items-stretch` on the grid and
+          `h-full` on each card so the tallest annotation still pins
+          every row member to a single baseline. The `min-h-[300px]`
+          floor stays in place for the single-column mobile view. */}
+      <div className="grid grid-cols-1 gap-4 md:auto-rows-fr md:grid-cols-3 md:items-stretch">
         <div
           data-slot="trends-row-card"
           data-metric="bp"
-          className="flex min-h-[300px] flex-col gap-2"
+          className="flex h-full min-h-[300px] flex-col gap-2"
         >
           <HealthChart
             types={["BLOOD_PRESSURE_SYS", "BLOOD_PRESSURE_DIA"]}
@@ -123,7 +127,7 @@ export function TrendsRow({ annotations, confidence }: TrendsRowProps) {
         <div
           data-slot="trends-row-card"
           data-metric="weight"
-          className="flex min-h-[300px] flex-col gap-2"
+          className="flex h-full min-h-[300px] flex-col gap-2"
         >
           <HealthChart
             types={["WEIGHT"]}
@@ -141,7 +145,7 @@ export function TrendsRow({ annotations, confidence }: TrendsRowProps) {
         <div
           data-slot="trends-row-card"
           data-metric="mood"
-          className="flex min-h-[300px] flex-col gap-2"
+          className="flex h-full min-h-[300px] flex-col gap-2"
         >
           <MoodChart title={t("charts.mood")} mini />
           <TrendAnnotation