refactor(discord): remove rich presence and bundled SDK

Remove the presence setting, platform bridge, SDK archive, and SDK preparation from local and CI builds. Reject leftover Discord native libraries in release APK audits.

android/app/src/androidTest/kotlin/com/zarz/spotiflac/discord/DiscordPresenceTest.kt

@@ -1,54 +0,0 @@
-package com.zarz.spotiflac.discord
-
-import android.content.Intent
-import androidx.test.ext.junit.runners.AndroidJUnit4
-import androidx.test.platform.app.InstrumentationRegistry
-import com.zarz.spotiflac.BuildConfig
-import com.zarz.spotiflac.MainActivity
-import org.junit.Assert.assertEquals
-import org.junit.Assert.assertTrue
-import org.junit.Assume.assumeTrue
-import org.junit.Test
-import org.junit.runner.RunWith
-
-/** Exercises the actual JNI library/SDK in the emulator, without account credentials. */
-@RunWith(AndroidJUnit4::class)
-class DiscordPresenceTest {
-    @Test
-    fun testSdkLifecycleAndLateCallbacks() {
-        val instrumentation = InstrumentationRegistry.getInstrumentation()
-        assumeTrue("Build with SPOTIFLAC_DISCORD_SDK_DIR", BuildConfig.HAS_DISCORD_SDK)
-        assumeTrue("This test must not publish to a signed-in account",
-            instrumentation.targetContext.packageManager.getLaunchIntentForPackage("com.discord") == null)
-        val activity = instrumentation.startActivitySync(
-            Intent(instrumentation.targetContext, MainActivity::class.java)
-                .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
-        )
-        try {
-            instrumentation.runOnMainSync {
-                assertEquals("discord_missing", DiscordPresenceBridge.configure(activity, true))
-                assertEquals("disabled", DiscordPresenceBridge.configure(activity, false))
-                System.loadLibrary("spotiflac_discord")
-                Class.forName("com.discord.socialsdk.DiscordSocialSdkInit")
-                    .getMethod("setEngineActivity", android.app.Activity::class.java)
-                    .invoke(null, activity)
-                DiscordNative.start(1549854098801692862L)
-                DiscordNative.update("Track 🎵", "Lead & Guest", "Album", "", 1000, 2000)
-                DiscordNative.clear()
-                DiscordNative.stop()
-            }
-            repeat(20) {
-                Thread.sleep(50)
-                instrumentation.runOnMainSync { assertEquals("disabled", DiscordNative.poll()) }
-            }
-            instrumentation.runOnMainSync {
-                DiscordNative.start(1549854098801692862L)
-                assertEquals("ready", DiscordNative.poll())
-                DiscordNative.stop()
-                assertEquals("disabled", DiscordNative.poll())
-            }
-        } finally {
-            instrumentation.runOnMainSync { activity.finish() }
-        }
-    }
-}