fix: add ndkVersion to app/build.gradle and remove useless NDK step from workflow

Agent-Logs-Url: https://github.com/michelhe/rustboyadvance-ng/sessions/efca739a-e81e-4485-9769-3d383fdf0d5b

Co-authored-by: michelhe <2903914+michelhe@users.noreply.github.com>

Author: Copilot

.github/workflows/build.yml

@@ -96,9 +96,6 @@ jobs:
         path: target
         key: ${{ runner.os }}-android-cargo-build-target-${{ hashFiles('**/Cargo.lock') }}
 
-    - name: Setup Android NDK
-      run: echo "ANDROID_NDK_HOME=$ANDROID_NDK_HOME" >> $GITHUB_ENV
-
     - name: Build APK
       working-directory: ./platform/android
       run: ./gradlew assembleRelease

platform/android/app/build.gradle

@@ -3,6 +3,7 @@ apply plugin: 'com.android.application'
 android {
     namespace 'com.mrmichel.rustdroid_emu'
     compileSdk 36
+    ndkVersion "27.3.13750724"
     defaultConfig {
         applicationId "com.mrmichel.rustdroid_emu"
         minSdk 21