Fix emulator CI: install all Rust Android targets

The Gradle build compiles native code for all 4 ABIs regardless of
which emulator architecture is used, so all targets are needed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: madeye

.github/workflows/build.yml

@@ -146,7 +146,7 @@ jobs:
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
         with:
-          targets: x86_64-linux-android
+          targets: armv7-linux-androideabi,aarch64-linux-android,i686-linux-android,x86_64-linux-android
 
       - name: Cache cargo registry and build
         uses: actions/cache@v4