- Add proton-bridge as optional dep behind `proton` feature flag
- New proton-bridge/src/lib.rs: pub fn start() spins a background Tokio
thread, pre-binds ports, and signals readiness via mpsc before returning
- src/main.rs: conditionally starts bridge before TUI enters raw mode;
derives effective IMAP/SMTP config via Provider enum
- src/config.rs: add Provider enum, optional imap/smtp, ProtonConfig/
BridgeConfig mirrors, effective_imap/smtp() helpers
- Remove all per-operation eprintln!/println! from imap_server, smtp_server,
and api.rs that fired during TUI operation and corrupted the display
- config.toml.example: unified format covering both imap and proton providers
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
