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/version.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# Prints the release version used to name both dist/shockolate-*.tar.gz
+# (see `make package`) and dist/questshock-*.apk (see build-apk.sh), so
+# the two are always versioned identically.
+#
+# Defaults to the current git tag (vX.Y.Z, prefix stripped) if HEAD is
+# exactly on one matching that pattern; otherwise a 0.0.0-dev+<sha>
+# placeholder (with a warning on stderr) - push a vX.Y.Z tag to drive a
+# real release version. Override either way with VERSION=1.2.3 in the
+# environment.
+set -euo pipefail
+
+V="${VERSION:-}"
+if [ -z "$V" ]; then
+    if TAG=$(git describe --tags --exact-match --match 'v[0-9]*.[0-9]*.[0-9]*' 2>/dev/null); then
+        V="${TAG#v}"
+    else
+        V="0.0.0-dev+$(git rev-parse --short HEAD)"
+        echo "WARNING: HEAD is not on a vX.Y.Z tag - building placeholder version $V (push a tag to drive a real release version)" >&2
+    fi
+fi
+
+case "$V" in
+    [0-9]*.[0-9]*.[0-9]*) ;;
+    *) echo "PREFLIGHT FAIL: VERSION '$V' is not a semantic version (expected X.Y.Z, optionally with a -pre+meta suffix)" >&2; exit 1;;
+esac
+
+echo "$V"