fix(years): format academic years as 2016/17 across all views, remove legacy frontend and data

Apply formatAcademicYear to all year displays in ComparisonChart, ComparisonView,
PerformanceChart, and RankingsView. Remove old vanilla JS frontend and CSV data
directory — both superseded by the Next.js app and Meltano pipeline.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nextjs-app/components/ComparisonView.tsx

@@ -13,7 +13,7 @@ import { SchoolSearchModal } from './SchoolSearchModal';
 import { EmptyState } from './EmptyState';
 import { LoadingSkeleton } from './LoadingSkeleton';
 import type { ComparisonData, MetricDefinition, School } from '@/lib/types';
-import { formatPercentage, formatProgress, CHART_COLORS, schoolUrl } from '@/lib/utils';
+import { formatPercentage, formatProgress, formatAcademicYear, CHART_COLORS, schoolUrl } from '@/lib/utils';
 import { fetchComparison } from '@/lib/api';
 import styles from './ComparisonView.module.css';
 
@@ -392,7 +392,7 @@ export function ComparisonView({
                   <tbody>
                     {years.map((year) => (
                       <tr key={year}>
-                        <td className={styles.yearCell}>{year}</td>
+                        <td className={styles.yearCell}>{formatAcademicYear(year)}</td>
                         {activeSchools.map((school) => {
                           const schoolData = activeComparisonData[school.urn];
                           if (!schoolData) return <td key={school.urn}>-</td>;