privacy.hideProviders and hideUsers are accepted but never enforced

[rowkav09]

validatePrivacyPolicy accepts hideProviders (default true) and hideUsers, but applyPrivacy in src/privacy.js never reads them. The provider id stays on the presence, so {provider} and {service} (and the default Discord name "{artist} on {service}") still show the source name, e.g. Jellyfin, even with the flags on.

Fix: apply both flags in applyPrivacy, with fail-first tests, as its own change.

[rowkav09]

Checked reachability: the app config only accepts redactTitles, hideArtwork and hideProgress (src/setup-config.js PRIVACY_FLAGS), so a user cannot set hideProviders or hideUsers through config.json or Settings. They only exist as library defaults, and hideProviders defaults to true.

So enforcing them as written would blank {provider}/{service} for everyone by default and remove the "{artist} on {service}" header. A real fix needs a decision first: change the default to false and add a Settings switch ("hide the service name"), or drop the dead flags. Not changing anything until that is decided.