Add lib-decoder-ffmpeg to app:phone

I cannot get the androidx.media3 ffmpeg decoder to compile nicely to upload it to maven central. So for now the prebuilt aar stays in this repo.

app/phone/build.gradle.kts

@@ -107,4 +107,6 @@ dependencies {
     compileOnly(libs.libmpv)
     implementation(libs.material)
     implementation(libs.timber)
+
+    implementation(rootProject.files("libs/lib-decoder-ffmpeg-release.aar"))
 }