cache.js: Map values serialise as '{}' under JSON.stringify, causing
emby:users to show 0 bytes and null item count in the status panel.
Convert Maps via Object.fromEntries before stringifying, and report
Map.size as itemCount.
index.js: JS and CSS served with Cache-Control: no-cache so browsers
always revalidate on load. ETag still prevents re-downloading unchanged
files — only a new deploy triggers an actual download.