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>

public/index.html

@@ -1349,13 +1349,13 @@ function saveHeroMeta() {
   });
 })();
 
-function uploadHeroImage(input) {
+async function uploadHeroImage(input) {
   const file = input.files[0];
   if (!file) return;
   const reader = new FileReader();
-  reader.onload = (e) => {
+  reader.onload = async (e) => {
     const img = new Image();
-    img.onload = () => {
+    img.onload = async () => {
       const maxW = 1600;
       let w = img.width, h = img.height;
       if (w > maxW) { h = Math.round(h * maxW / w); w = maxW; }
@@ -1363,11 +1363,25 @@ function uploadHeroImage(input) {
       canvas.width = w; canvas.height = h;
       canvas.getContext('2d').drawImage(img, 0, 0, w, h);
       const dataUrl = canvas.toDataURL('image/jpeg', 0.85);
-      applyHeroImage(dataUrl);
-      heroMeta.posY = 50;
-      applyHeroMeta();
-      saveVisionSection('hero-image', dataUrl);
-      saveHeroMeta();
+
+      // Upload file to server (too large for NocoDB LongText)
+      try {
+        const res = await fetch('/api/hero-upload', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ dataUrl }),
+        });
+        const data = await res.json();
+        if (data.path) {
+          applyHeroImage(data.path);
+          heroMeta.posY = 50;
+          applyHeroMeta();
+          saveVisionSection('hero-image', data.path);
+          saveHeroMeta();
+        }
+      } catch (err) {
+        console.error('Hero upload error:', err);
+      }
     };
     img.src = e.target.result;
   };