Improve gallery video UX and add upload-to-publish media workflow.

Stage raw files in upload/, publish with make sync-media/publish, and polish the lightbox: autoplay, remembered volume, Escape to close, and image/video icons without poster or caption clutter.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/internal/gallery/media.go

@@ -15,6 +15,9 @@ func isVideo(name string) bool {
 }
 
 func isGalleryMedia(name string) bool {
+	if isWebDerivative(name) {
+		return false
+	}
 	return isJPEG(name) || isVideo(name)
 }
 
@@ -34,3 +37,7 @@ func videoPosterRel(rel string) string {
 	}
 	return strings.TrimSuffix(rel, ext) + ".jpg"
 }
+
+func isWebDerivative(name string) bool {
+	return strings.HasSuffix(strings.ToLower(name), ".web.mp4")
+}