Pre-Alfa-Test-Windows

Pre-alpha release: PKCE OAuth2, Google Drive sync, peer discovery

Features:
- OAuth2 authentication with PKCE + ClientSecret (installed apps)
- Google Drive contacts synchronization
- Real P2P peer discovery with libp2p
- Local peer history persistence
- Memory-efficient hybrid architecture
- Privacy by design
- GDPR compliant

Setup: See OAUTH_PKCE_SETUP.md and PRIVACY_POLICY.md