- Use hyper-client to avoid isahc/coarsetime (AtomicU64 on MIPS)
- Keep push notifications enabled for MIPS builds
- Update CI MIPS build to use default features
- Add push-notifications feature flag (enabled by default)
- Make web-push and openssl optional dependencies
- Conditionally compile push notification code
- Disable push notifications for MIPS builds in CI
- Fixes AtomicU64 error on 32-bit MIPS architecture
- x86_64/ARM builds still have full push notification support
