ci: ensure Android NDK is available in build-and-test job

Set ANDROID_HOME/NDK_HOME/NDK_VERSION at the job level and add a step
that installs the NDK via sdkmanager when missing, so the Android init
step no longer fails when the builder image lacks NDK_HOME.

.gitea/workflows/build-and-test.yml

@@ -66,6 +66,10 @@ jobs:
     needs: test
     container:
       image: gitea.tourolle.paris/dtourolle/jellytau-builder:latest
+    env:
+      ANDROID_HOME: /opt/android-sdk
+      NDK_VERSION: 27.0.11902837
+      NDK_HOME: /opt/android-sdk/ndk/27.0.11902837
 
     steps:
       - name: Checkout repository
@@ -99,6 +103,15 @@ jobs:
       - name: Build frontend
         run: bun run build
 
+      - name: Ensure Android NDK
+        run: |
+          if [ ! -d "$NDK_HOME" ]; then
+            echo "NDK not found at $NDK_HOME, installing ndk;$NDK_VERSION"
+            yes | "$ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager" --sdk_root="$ANDROID_HOME" "ndk;$NDK_VERSION"
+          fi
+          echo "Using NDK at $NDK_HOME"
+          ls "$NDK_HOME"
+
       - name: Initialize Android project
         run: |
           cd src-tauri