fix(insights): rename the review section and even its top spacing

Shorten the period-narrative section title to 'Rückblick' (and the idiomatic
short equivalent per locale) — the same i18n key the customizable-overview
edit-mode labels read, so the rename flows through automatically.

Drop the redundant 300px min-height floor on the Trends cards. The chart slot
is a fixed 180px and the caption is clamped to three lines, so the floor
padded dead space below every caption that read as an oversized Trends to
Rückblick seam. The grid's auto-rows-fr plus the fixed chart slot already pin
the cards to a single baseline, so the seam now matches the uniform rhythm.

src/components/insights/trends-row.tsx

@@ -243,7 +243,16 @@ export function TrendsRow({
               key={config.metric}
               data-slot="trends-row-card"
               data-metric={config.metric}
-              className="flex h-full flex-col gap-2 md:min-h-[300px]"
+              // v1.15.12 D1 — drop the `md:min-h-[300px]` floor. The chart
+              // slot is a fixed 180 px and the caption is `line-clamp-3`, so a
+              // card's natural height tops out around 270 px; the 300 px floor
+              // padded ~30 px of dead space below every caption, which read as
+              // an oversized Trends→Rückblick seam (the `space-y-6` gap is even,
+              // the empty card tail was the culprit). `auto-rows-fr` +
+              // `md:items-stretch` on the grid already pin every card to a
+              // single baseline, and the fixed chart slot aligns the charts, so
+              // the floor was redundant. Cards now size to content.
+              className="flex h-full flex-col gap-2"
             >
               {/* v1.4.28 R3c-Insights — fixed chart slot. The mini
                   chart paints its own band; this wrapper pins the