Build native ripgrep in Android workflow

[luojiaping]

What changed

• trigger the Android workflow when the native ripgrep crate changes
• cache Cargo dependencies and Android release artifacts
• cross-compile liboperit_ripgrep.so for arm64-v8a before Gradle runs
• verify the generated library exists before continuing

Why

grep_code now loads the Rust JNI library, but the GitHub Actions workflow only restored the older jniLibs.zip. As a result, a successful APK build could omit liboperit_ripgrep.so and crash at runtime with UnsatisfiedLinkError.

Validation

• parsed the workflow as YAML
• passed git diff --check
• validated the equivalent Rust/NDK cross-compile on the cloud builder and confirmed the resulting APK contains lib/arm64-v8a/liboperit_ripgrep.so