Fix hero image persistence: file upload instead of NocoDB base64

NocoDB LongText field has ~95KB limit, hero image is ~456KB base64.
New approach: POST /api/hero-upload saves image as file in /public/uploads/,
NocoDB stores only the path. Docker volume configured for persistence.

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

server.js

@@ -239,6 +239,28 @@ app.put('/api/contenu/:sceneId', requireAuth, async (req, res) => {
   }
 });
 
+// ── Hero image upload (file too large for NocoDB LongText) ──
+const fs = require('fs');
+
+app.post('/api/hero-upload', requireAuth, (req, res) => {
+  try {
+    const { dataUrl } = req.body;
+    if (!dataUrl || !dataUrl.startsWith('data:image/')) return res.status(400).json({ error: 'Invalid image' });
+    const matches = dataUrl.match(/^data:image\/(\w+);base64,(.+)$/);
+    if (!matches) return res.status(400).json({ error: 'Invalid format' });
+    const ext = matches[1] === 'jpeg' ? 'jpg' : matches[1];
+    const buffer = Buffer.from(matches[2], 'base64');
+    const uploadDir = path.join(__dirname, 'public', 'uploads');
+    if (!fs.existsSync(uploadDir)) fs.mkdirSync(uploadDir, { recursive: true });
+    const filename = `hero.${ext}`;
+    fs.writeFileSync(path.join(uploadDir, filename), buffer);
+    const publicPath = `/uploads/${filename}?t=${Date.now()}`;
+    res.json({ path: publicPath });
+  } catch (e) {
+    res.status(500).json({ error: e.message });
+  }
+});
+
 // Auth gate — redirect to login page if not authenticated
 app.get('/', (req, res) => {
   if (isAuth(req)) {