codecs: add native build scripts for libvpx/opus/speex + fix CMake includes

- scripts/build-native-codecs.sh: cross-compile libvpx, opus, speex for
  Android ABIs (arm64-v8a, armeabi-v7a, x86_64) using NDK clang with -fPIC
- scripts/android-ndk.sh: NDK root detection helper
- scripts/native-build-cache.sh: ccache detection helper
- scripts/init-third-party-submodules.sh: init codec submodules
- scripts/ensure-gradle-wrapper.sh: gradle wrapper sanity check
- scripts/adb-reconnect.sh: ADB device discovery helpers
- ndk/CMakeLists.txt: per-ABI include dirs for opus/ and speex_config_types.h

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/ensure-gradle-wrapper.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# Verify gradlew wrapper exists and is executable. Exit non-zero if missing.
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+
+if [[ ! -x "$ROOT/gradlew" ]]; then
+  echo "ERROR: gradlew wrapper not found at $ROOT/gradlew" >&2
+  echo "       Run: gradle wrapper --gradle-version 8.9 (from $ROOT)" >&2
+  exit 1
+fi
+echo "==> Gradle wrapper OK: $ROOT/gradlew"