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/android-ndk.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+# Locate Android NDK root for the project. Source this file.
+# Usage: export ANDROID_NDK_HOME="$(androidcast_find_ndk_root "$ROOT")"
+
+androidcast_find_ndk_root() {
+  local project_root="${1:-$PWD}"
+  local lp="$project_root/local.properties"
+
+  # Prefer local.properties ndk.dir
+  if [[ -f "$lp" ]]; then
+    local ndk_dir
+    ndk_dir="$(grep '^ndk\.dir=' "$lp" 2>/dev/null | cut -d= -f2 | tr -d '[:space:]')"
+    if [[ -n "$ndk_dir" && -d "$ndk_dir" ]]; then
+      echo "$ndk_dir"
+      return 0
+    fi
+  fi
+
+  # ANDROID_NDK_HOME / ANDROID_NDK_ROOT env
+  for v in "${ANDROID_NDK_HOME:-}" "${ANDROID_NDK_ROOT:-}"; do
+    if [[ -n "$v" && -d "$v" ]]; then
+      echo "$v"
+      return 0
+    fi
+  done
+
+  # Search SDK
+  local sdk_root="${ANDROID_HOME:-${ANDROID_SDK_ROOT:-$HOME/Android/Sdk}}"
+  if [[ -d "$sdk_root/ndk" ]]; then
+    # Prefer NDK 29, then highest available
+    for preferred in 29 28 27 26; do
+      local match
+      match="$(ls "$sdk_root/ndk" 2>/dev/null | grep "^${preferred}\." | sort -V | tail -1)"
+      if [[ -n "$match" && -d "$sdk_root/ndk/$match" ]]; then
+        echo "$sdk_root/ndk/$match"
+        return 0
+      fi
+    done
+    local latest
+    latest="$(ls "$sdk_root/ndk" 2>/dev/null | sort -V | tail -1)"
+    if [[ -n "$latest" && -d "$sdk_root/ndk/$latest" ]]; then
+      echo "$sdk_root/ndk/$latest"
+      return 0
+    fi
+  fi
+
+  echo "ERROR: Android NDK not found. Install via Android Studio SDK Manager or set ANDROID_NDK_HOME." >&2
+  return 1
+}