Existing PWA installs cache the app shell (app.js et al.) cache-first under
ytplayer-v1.0.0. Without a version bump they'd keep serving the old app.js
that lacked WEB-mode OPFS support, so the offline-cache fix would never reach
already-installed clients. Bumping forces activate → old cache delete →
re-fetch, and triggers the in-app 'Update ready' banner.
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