[maxrave-dev]

What & why

Full builds now show Discord Rich Presence under SimpMusic's own Discord application, signed in through Discord's OAuth flow instead of kizzy's token login. The new module core/service/discord asks for openid sdk.social_layer_presence, the minimum scope Discord documents for Rich Presence, and sets the activity over the gateway with the Bearer token. Discord's consent screen lists the whole presence bundle (friends, invites); the app only connects to the gateway, updates the activity and registers artwork through external-assets. FOSS builds keep kizzy unchanged.

The application id stays out of the source: it is read from DISCORD_CLIENT_ID in local.properties through BuildKonfig, and every Full CI job writes it from the repository secret of the same name.

The submodule points at feature/discord-oauth in maxrave-dev/core, which is not in multiplatform yet. The branch also carries 53cb9cc (core bump for removed and cancelled downloads going back to not downloaded), which had not reached dev yet.

Linked issue

None.

Checklist

• This PR addresses an accepted issue (linked above)
• I wrote or personally reviewed every line of this change
• I tested it on Android and/or Desktop (say which, and how): Android, Full build, on a real device: signed in to Discord over OAuth.