fix(android): bundle Discord SDK in local and CI releases

.github/actions/discord-sdk/action.yml

@@ -0,0 +1,17 @@
+name: Prepare Discord Social SDK
+description: Decrypt and verify the pinned Android SDK before Gradle configures native builds.
+inputs:
+  passphrase:
+    description: Decryption key for the bundled Android SDK, supplied from a repository secret.
+    required: true
+runs:
+  using: composite
+  steps:
+    - name: Decrypt and verify SDK
+      shell: bash
+      env:
+        DISCORD_SDK_PASSPHRASE: ${{ inputs.passphrase }}
+      run: |
+        set -euo pipefail
+        sdk_dir="$(python3 scripts/prepare_discord_sdk.py)"
+        printf 'SPOTIFLAC_DISCORD_SDK_DIR=%s\n' "$sdk_dir" >> "$GITHUB_ENV"