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.

scripts/build_android.sh

@@ -8,8 +8,6 @@ PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
 OUTPUT_DIR="$PROJECT_DIR/build/app/outputs/flutter-apk"
 
 cd "$PROJECT_DIR"
-SPOTIFLAC_DISCORD_SDK_DIR="$(python3 scripts/prepare_discord_sdk.py)"
-export SPOTIFLAC_DISCORD_SDK_DIR
 BUILD_GIT_COMMIT="$(git rev-parse --short=8 HEAD)"
 flutter build apk \
   --release \
@@ -30,7 +28,7 @@ for target in armeabi-v7a arm64-v8a universal; do
     exit 1
   fi
   python3 scripts/check_backend_apk.py "$OUTPUT_DIR/$apk" \
-    --backend rust --abis "$abis" --require-discord
+    --backend rust --abis "$abis"
 done
 
 echo "Built Android release APKs in $OUTPUT_DIR"