perf(android): reduce release APK size

Keep Dart debug data outside libapp.so and archive matching symbols and R8 mappings in CI. Pack native relocations, preserve JNI exports, and recompress PNG assets losslessly.

ARM64 APK shrinks from 80,306,680 to 76,080,247 bytes (5.26%). Verified with 1,877 Flutter tests, 19 native device tests, Discord SDK integration, and release startup on a 16 KiB Android emulator.

.github/workflows/ci.yml

@@ -313,3 +313,21 @@ jobs:
             "$ANDROID_HOME/build-tools/37.0.0/apksigner" verify --verbose \
               "build/app/outputs/flutter-apk/app-${abi}-release.apk"
           done
+
+      - name: Record Android symbol provenance
+        run: |
+          test -s build/symbols/android/app.android-arm64.symbols
+          test -s build/symbols/android/app.android-arm.symbols
+          test -s build/app/outputs/mapping/release/mapping.txt
+          git rev-parse HEAD > build/symbols/android/commit.txt
+          sha256sum build/app/outputs/flutter-apk/*release.apk > build/symbols/android/apk-sha256.txt
+
+      - name: Retain Android debug symbols
+        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6
+        with:
+          name: android-symbols-${{ github.sha }}-${{ github.run_id }}-${{ github.run_attempt }}
+          if-no-files-found: error
+          retention-days: 90
+          path: |
+            build/symbols/android/
+            build/app/outputs/mapping/release/mapping.txt

.github/workflows/release.yml

@@ -227,6 +227,24 @@ jobs:
               "$apk_dir/SpotiFLAC-${VERSION}-${abi}.apk"
           done
 
+      - name: Record Android symbol provenance
+        run: |
+          test -s build/symbols/android/app.android-arm64.symbols
+          test -s build/symbols/android/app.android-arm.symbols
+          test -s build/app/outputs/mapping/release/mapping.txt
+          git rev-parse HEAD > build/symbols/android/commit.txt
+          sha256sum build/app/outputs/flutter-apk/SpotiFLAC-*.apk > build/symbols/android/apk-sha256.txt
+
+      - name: Retain Android debug symbols
+        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6
+        with:
+          name: android-symbols-${{ needs.get-version.outputs.version }}-${{ github.sha }}-${{ github.run_id }}-${{ github.run_attempt }}
+          if-no-files-found: error
+          retention-days: 90
+          path: |
+            build/symbols/android/
+            build/app/outputs/mapping/release/mapping.txt
+
       - name: Upload APK artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6
         with: