Add full-image lightbox and restore WLED state on stop

- Add GET /picture-streams/full-image endpoint to serve full-res images
- Click static image preview thumbnail to open full-res lightbox
- Snapshot WLED state (on/off, lor, AudioReactive) before streaming
- Restore saved WLED state when streaming stops

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

server/src/wled_controller/static/app.js

@@ -81,11 +81,28 @@ function closeLightbox(event) {
     if (event && event.target && event.target.closest('.lightbox-content')) return;
     const lightbox = document.getElementById('image-lightbox');
     lightbox.classList.remove('active');
-    document.getElementById('lightbox-image').src = '';
+    const img = document.getElementById('lightbox-image');
+    // Revoke blob URL if one was used
+    if (img.src.startsWith('blob:')) URL.revokeObjectURL(img.src);
+    img.src = '';
     document.getElementById('lightbox-stats').style.display = 'none';
     unlockBody();
 }
 
+async function openFullImageLightbox(imageSource) {
+    try {
+        const resp = await fetch(`${API_BASE}/picture-streams/full-image?source=${encodeURIComponent(imageSource)}`, {
+            headers: getHeaders()
+        });
+        if (!resp.ok) return;
+        const blob = await resp.blob();
+        const blobUrl = URL.createObjectURL(blob);
+        openLightbox(blobUrl);
+    } catch (err) {
+        console.error('Failed to load full image:', err);
+    }
+}
+
 document.addEventListener('keydown', (e) => {
     if (e.key === 'Escape') {
         // Close in order: overlay lightboxes first, then modals
@@ -3627,6 +3644,8 @@ async function validateStaticImage() {
         _lastValidatedImageSource = source;
         if (data.valid) {
             previewImg.src = data.preview;
+            previewImg.style.cursor = 'pointer';
+            previewImg.onclick = () => openFullImageLightbox(source);
             infoEl.textContent = `${data.width} × ${data.height} px`;
             previewContainer.style.display = '';
             statusEl.textContent = t('streams.validate_image.valid');