ci(android): install the SDK CMake package so cargo-ndk can build libopus

The android.yml runner installed the NDK but not cmake/ninja, so cargo-ndk's audiopus_sys
(libopus via CMake) failed with "is `cmake` not installed?" — broken since the audio increment
added the libopus dependency. kit/build.gradle.kts prepends $ANDROID_SDK/cmake/3.22.1/bin to
PATH (the same SDK CMake that makes local builds work); install cmake;3.22.1 (cmake + ninja) so
that path exists in CI too. Also pin platforms;android-37 to match compileSdk (AGP auto-installs
it otherwise).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/android.yml

@@ -41,8 +41,11 @@ jobs:
       - name: Android SDK
         uses: android-actions/setup-android@v3
 
-      - name: NDK r28 LTS + platform 36 + build-tools
-        run: sdkmanager "platform-tools" "platforms;android-36" "build-tools;36.0.0" "ndk;28.2.13676358"
+      - name: NDK r28 LTS + platform 37 + build-tools + CMake (libopus cross-build)
+        # cmake;3.22.1 installs cmake + ninja under $ANDROID_SDK/cmake/3.22.1/bin — the exact path
+        # kit/build.gradle.kts prepends to PATH for cargo-ndk's audiopus_sys (libopus) CMake build.
+        # platform 37 matches compileSdk (AGP auto-installs it too, but pin it for a warm cache).
+        run: sdkmanager "platform-tools" "platforms;android-37" "build-tools;36.0.0" "ndk;28.2.13676358" "cmake;3.22.1"
 
       - name: Caches (cargo + gradle)
         uses: actions/cache@v4