release builds shrink with R8: 65 MB down to 30 MB, small enough for IzzyOnDroid. -Pr8 does the same to a debug build for testing

gearslip/proguard-rules.pro

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+# R8 shrinks the release build; these keep what it can't see being used.
+
+# Names stay readable, so stack traces in shared logs need no mapping file. Shrinking does
+# the real work on size.
+-dontobfuscate
+
+# Gearslip hosts other apps' car screens: their templates arrive as Bundles, and the car
+# library rebuilds them by class name and reflection. Any model class an app might send has to
+# survive, used by Gearslip's code or not.
+-keep class androidx.car.app.** { *; }
+
+# Speech-to-text: the native library calls back into these classes by name.
+-keep class com.k2fsa.sherpa.onnx.** { *; }
+
+# commons-compress refers to optional codecs Gearslip doesn't ship.
+-dontwarn org.tukaani.xz.**
+-dontwarn com.github.luben.zstd.**
+-dontwarn org.brotli.dec.**
+-dontwarn org.objectweb.asm.**
+-dontwarn org.osgi.**