The hand-rolled SVG sparkline used px font sizes inside a 520-wide viewBox
that stretched to the full card width, so labels ballooned ~4x and collided —
and with 10+ years of real data the per-point labels and year ticks
overlapped badly, while the oversized chart stretched the "this year" view.
Replace it with a Chart.js line chart (AdmissionsTrendChart) in a fixed
200px wrapper, matching PerformanceChart: responsive px fonts, auto-skipping
x ticks, auto-scaled y-axis clamped to 0-100, emphasised latest point.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The school detail page only showed the latest admissions year. We store
every year, which is more decision-relevant for parents (the trend and its
consistency matter more than a single noisy year).
Backend now returns the full admissions_history (oldest first) alongside the
existing latest-year object. The primary SchoolDetailView gains a header
toggle ("This year | N-year trend") that swaps the Q&A for an SVG sparkline
of the first-choice offer rate. The toggle only appears when >=2 years carry
an offer rate; otherwise it falls back to the single-year card. Both views
share one CSS-grid cell so switching causes no layout shift.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>