fix(admissions): render trend with Chart.js instead of scaled SVG

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>

nextjs-app/components/SchoolDetailView.module.css

@@ -1381,49 +1381,6 @@
     margin-bottom: 0.5rem;
 }
 
-.admissionsChart {
-    width: 100%;
-    height: auto;
-    display: block;
-}
-
-.admissionsGrid {
-    stroke: var(--border-color, #e5dfd5);
-    stroke-width: 1;
-}
-
-.admissionsAxis {
-    font-size: 12.5px;
-    fill: var(--text-muted, #6d685f);
-    font-family: var(--font-dm-sans), "DM Sans", sans-serif;
-}
-
-.admissionsLine {
-    stroke: var(--accent-coral, #e07256);
-    stroke-width: 3;
-}
-
-.admissionsDot {
-    fill: var(--accent-coral, #e07256);
-}
-
-.admissionsDotLast {
-    fill: var(--accent-coral, #e07256);
-    stroke: var(--bg-card, #fff);
-    stroke-width: 2;
-}
-
-.admissionsPtLabel {
-    font-size: 13px;
-    font-weight: 700;
-    fill: var(--text-primary, #1a1612);
-    font-family: var(--font-dm-sans), "DM Sans", sans-serif;
-}
-
-.admissionsPtLabel[data-last="true"] {
-    fill: var(--accent-coral-dark, #c45a3f);
-}
-
 .admissionsTrendSummary {
     font-size: 1rem;
     color: var(--text-secondary, #5c564d);