Fix Quest launch crashes, version the APK like the tarball, and support native builds in Android Studio

- patchelf gl4es's embedded SONAME to libGL.so so AGP's jniLibs packaging
  (which drops any file not literally named "*.so") and the dynamic
  linker's NEEDED-entry resolution (by embedded SONAME, not filename)
  finally agree - fixes the "library \"libGL.so.1\" not found" crash seen
  on real Quest hardware.
- QuestShockActivity now checks that res/data and res/sound exist before
  starting the native engine, showing an explanatory dialog instead of
  crashing on init_popups' unchecked NULL resource load when a fresh
  install has no game data copied in yet.
- dist/questshock-<version>-android-arm64.apk is now versioned from the
  same git-tag-or-dev-placeholder scheme as the desktop tarball
  (build-image/version.sh, shared by both via the Makefile and
  build-apk.sh).
- build-image/prepare-android-project.sh (prep logic extracted out of
  build-apk.sh) can now stage android/ for a native build directly in
  Android Studio (--host-paths), exporting the prebuilt SDL2/SDL2_mixer/
  fluidsynth-lite/gl4es libraries and writing host-resolvable paths,
  instead of only ever building inside the Docker image.
- Corrected GET_ASSETS.txt/GET_ASSETS_QUEST.txt, which wrongly described
  merging res/pc/hd and res/pc/cdrom trees out of the raw installer's
  sshock.kpf - an already-installed copy's res/data res/sound can just
  be copied directly, with extract_assets.sh only needed from the raw
  installer.

build-image/Dockerfile

@@ -77,12 +77,17 @@ ENV DEBIAN_FRONTEND=noninteractive
 # build cache for this layer - and vice versa, adding a package here only
 # ever costs a rebuild of the (slow) layers below it, not a re-download
 # of packages that didn't change.
+# patchelf: fixes up GL4ES's built-in ELF SONAME below (see the gl4es
+# build step) - the Android APK packager (AGP) refuses to bundle a
+# jniLibs file whose name doesn't literally end in ".so", but the
+# dynamic linker resolves NEEDED entries by embedded SONAME, not
+# filename - patchelf lets both agree on "libGL.so".
 RUN apt-get update && apt-get install -y --no-install-recommends \
         build-essential cmake make git curl ca-certificates pkg-config gosu \
         libgl1-mesa-dev libglx-dev libxext-dev libx11-dev libxrandr-dev \
         libxi-dev libxfixes-dev libxss-dev libxinerama-dev libxcursor-dev \
         libogg-dev libvorbis-dev libasound2-dev openssh-client \
-        openjdk-17-jdk-headless unzip \
+        openjdk-17-jdk-headless unzip patchelf \
     && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /opt/prebuilt
@@ -231,8 +236,17 @@ RUN git clone https://github.com/EtherTyper/fluidsynth-lite.git fluidsynth-lite-
 
 # gl4es's own CMakeLists.txt writes its output straight to
 # ${CMAKE_SOURCE_DIR}/lib (the source tree, not the build dir) and gives
-# the GL target a ".so.1" suffix - stage explicitly rather than
-# `cmake --install` (which it doesn't support for this target anyway).
+# the GL target a ".so.1" suffix, both in filename and in its embedded
+# ELF SONAME - stage explicitly rather than `cmake --install` (which it
+# doesn't support for this target anyway). Renaming the *file* to
+# "libGL.so" isn't enough on its own: the dynamic linker resolves
+# libmain.so's NEEDED entry by the *embedded* SONAME, not by whatever
+# filename it was linked against, so a bare rename would link fine but
+# fail to dlopen on-device. And keeping the real "libGL.so.1" filename
+# isn't an option either - AGP's jniLibs packaging silently drops any
+# native library whose filename doesn't literally end in ".so". So
+# patchelf the embedded SONAME to "libGL.so" too, making the rename
+# consistent both at link time and at runtime.
 RUN git clone --branch "v${ANDROID_GL4ES_VERSION}" --depth 1 \
         https://github.com/ptitSeb/gl4es.git gl4es-android \
     && rm -rf gl4es-android/.git \
@@ -243,6 +257,7 @@ RUN git clone --branch "v${ANDROID_GL4ES_VERSION}" --depth 1 \
     && cmake --build build-gl4es-android -j"$(nproc)" \
     && mkdir -p /opt/prebuilt/android/gl4es/lib /opt/prebuilt/android/gl4es/include \
     && cp -a gl4es-android/lib/libGL.so.1 /opt/prebuilt/android/gl4es/lib/libGL.so \
+    && patchelf --set-soname libGL.so /opt/prebuilt/android/gl4es/lib/libGL.so \
     && cp -a gl4es-android/include/. /opt/prebuilt/android/gl4es/include/ \
     && rm -rf gl4es-android build-gl4es-android