feat(atproto-oauth-dioxus): add tracing logging, zeroize support, and cleanup deps
- Add tracing::error!() calls at all error sites in server.rs
- Add optional zeroize feature with ZeroizeOnDrop on ActiveSession
- Fix move-out-of-Drop errors when zeroize feature is enabled
- Add workspace dependency entry for atproto-oauth-dioxus
- Remove redundant serde features (already in workspace definition)