feat(cms): install Payload and serve the admin panel

Payload 3.88 runs inside the Next app against the existing Postgres, in
its own 'payload' schema so no pipeline operation on public — the app
tables, Airflow's metadata, migrate_csv_to_db.py --drop — can reach blog
content.

Its REST API is mounted at /cms-api. /api is the FastAPI proxy's
catch-all, which would swallow every admin call and forward it to the
backend with no error. The mount points live in lib/payloadRoutes.ts so
there is one definition and a test can assert it without importing
Payload: it is ESM-only, next/jest will not transform it, and appending
transformIgnorePatterns cannot un-ignore a package. Forcing it through
transpilePackages would change how the production build bundles Payload
to serve a test, so the live proof that /api still reaches FastAPI stays
where it belongs — the e2e journeys, which call /api/schools.

The package becomes ESM ("type": "module"), which Payload's CLI requires:
richtext-lexical has top-level await and the config cannot be require()d.
Only two files needed renaming, jest.config.cjs and a build script.

The build is verified to succeed with DATABASE_URL and PAYLOAD_SECRET
both unset, which is how CI builds it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017YmbBhr8s7GusjDE12hrZM

nextjs-app/scripts/build-hero-images.cjs

@@ -0,0 +1,114 @@
+#!/usr/bin/env node
+/**
+ * Derivatives for the landing hero artwork.
+ *
+ *   node scripts/build-hero-images.js
+ *
+ * Source of truth is assets/hero-source.png (1672×941). It is committed so
+ * these can be regenerated: never hand-edit anything in public/brand/hero-*,
+ * change the source or the numbers here and re-run.
+ *
+ * TWO CROPS, ON PURPOSE
+ * ---------------------
+ * The hero slot is not one shape. On desktop the artwork sits behind the whole
+ * panel at roughly 2.1:1 → 2.7:1; below the one-column breakpoint it collapses
+ * to a band between 2.6:1 and 4.9:1. A single file under `object-fit: cover`
+ * centre-crops, which at the extremes slices a strip through the middle of the
+ * scene and loses the schoolhouse — the same failure the previous SVG hero had.
+ *
+ * So:
+ *   wide  the full frame, including the empty cream area the artwork reserves
+ *         on the left for the headline. Used behind the desktop panel.
+ *   band  a crop around the schoolhouse and the path, already near 2.6:1, so
+ *         the narrow band barely crops it at all. The school sits at ~65%
+ *         across, which is why the CSS pairs this with object-position: 65%:
+ *         squeezing further toward 4.9:1 crops the empty sides, not the subject.
+ *
+ * AVIF and WebP are both emitted. This is flat-shaded vector-style artwork, so
+ * AVIF lands roughly an order of magnitude under the source PNG. Both crops
+ * also get a JPEG: the wide one backs the <img src>, and the band one backs a
+ * <source media> — without it a browser taking neither modern format would
+ * fall through to the desktop frame on a phone, since <img src> cannot vary by
+ * viewport.
+ *
+ * sharp is declared in devDependencies rather than leaned on as a transitive
+ * dependency of next. It does currently arrive that way, but relying on that
+ * means a Next upgrade can silently break this script — the same reasoning as
+ * the outputFileTracingIncludes note in next.config.js.
+ */
+
+const path = require('path');
+const fs = require('fs');
+const sharp = require('sharp');
+
+const SRC = path.join(__dirname, '..', 'assets', 'hero-source.png');
+const OUT = path.join(__dirname, '..', 'public', 'brand');
+
+/*
+ * Band crop, in source pixels, measured against the artwork rather than
+ * guessed: the schoolhouse spans roughly x 1420–1860, y 420–660, with its flag
+ * up at y 330.
+ *
+ * The crop is flush to the right edge because it has to be. The school sits at
+ * about 82% across the frame, so there is only ~140px of artwork to its right
+ * — not enough to centre it. Anchoring right and taking 1050px back puts the
+ * school at ~66% across the crop, which is what BAND_FOCUS_X below reports to
+ * the CSS so the narrowest band crops the empty left side rather than the
+ * subject.
+ */
+const BAND = { left: 656, top: 300, width: 1344, height: 420 };
+
+/** Where the schoolhouse lands in the band crop, for CSS object-position. */
+const BAND_FOCUS_X = Math.round(((1420 + 1860) / 2 - BAND.left) / BAND.width * 100);
+
+const WIDE_WIDTHS = [2000, 1400, 1000];
+const BAND_WIDTHS = [1344, 900, 600];
+
+async function emit(pipeline, name, width) {
+  const base = pipeline.clone().resize({ width, withoutEnlargement: true });
+  await base.clone().avif({ quality: 62, effort: 6 }).toFile(path.join(OUT, `${name}-${width}.avif`));
+  await base.clone().webp({ quality: 80, effort: 6 }).toFile(path.join(OUT, `${name}-${width}.webp`));
+  return width;
+}
+
+async function main() {
+  if (!fs.existsSync(SRC)) throw new Error(`missing source: ${SRC}`);
+  fs.mkdirSync(OUT, { recursive: true });
+
+  const meta = await sharp(SRC).metadata();
+  console.log(`source ${meta.width}×${meta.height}`);
+  console.log(`band focus x: ${BAND_FOCUS_X}% (keep .heroArt object-position in step)`);
+
+  const wide = sharp(SRC);
+  for (const w of WIDE_WIDTHS) await emit(wide, 'hero-wide', w);
+  // Fallback for the <img> itself. Flattened onto the artwork's own cream so a
+  // JPEG (no alpha) can never composite against black.
+  await sharp(SRC)
+    .resize({ width: 1400 })
+    .flatten({ background: '#FEF2E1' })
+    .jpeg({ quality: 82, mozjpeg: true })
+    .toFile(path.join(OUT, 'hero-wide-1400.jpg'));
+
+  const band = sharp(SRC).extract(BAND);
+  for (const w of BAND_WIDTHS) await emit(band, 'hero-band', w);
+  await sharp(SRC)
+    .extract(BAND)
+    .resize({ width: 900 })
+    .flatten({ background: '#FEF2E1' })
+    .jpeg({ quality: 82, mozjpeg: true })
+    .toFile(path.join(OUT, 'hero-band-900.jpg'));
+
+  const files = fs.readdirSync(OUT).filter(f => f.startsWith('hero-')).sort();
+  let total = 0;
+  for (const f of files) {
+    const { size } = fs.statSync(path.join(OUT, f));
+    total += size;
+    console.log(`  ${f.padEnd(24)} ${(size / 1024).toFixed(1)} kB`);
+  }
+  console.log(`total ${(total / 1024).toFixed(1)} kB across ${files.length} files`);
+}
+
+main().catch(err => {
+  console.error(err);
+  process.exit(1);
+});