rustclipsync-core 0.4.0

rustclipsync-core 0.4.0

This is a breaking Rust API and wire-protocol upgrade. Use RustClipSync Server
3.0.0, Desktop 0.5.0 or Omaclipsync 0.4.0 together. Older clients require server
2.0.0. Mobile applications and Fcitx input methods are released separately.

• Add protocol-3 device direction reports, separate pause state, WebSocket ACKs,
  authenticated HTTP fallback and fenced session/version negotiation.
• Receive only authorized per-device deliveries; reconnect backfill is the last
  eligible message within the server's configured window. Do not hardcode it.
• Add background receive APIs without reading clipboard snapshots; writes remain
  explicit opt-ins, and sensitive-content policy remains enforced.
• Keep ordinary receives working after marked-sensitive synchronization is disabled.
• Add opt-in durable conflict cancellation/skip recovery and detection of legacy
  outboxes before receive. Preserve local clipboard and reject stale retries;
  hosts retain responsibility for choosing recovery policy and fencing events.
• Preserve existing device identities and RCS1 encrypted state. Older state
  defaults the recovery marker to false. Rust API additions and required transport
  methods are a pre-1.0 minor API break; endpoint prefix remains /api/.

Validation: 68 Rust tests, rustfmt, strict Clippy, rustdoc, and actual core/server
HTTPS interoperability with real WSS and forced HTTP fallback. Consumer native
acceptance is documented in the respective repositories. This release is source
on GitHub; the crate is not published to crates.io.

rustclipsync-core 0.3.0

Shared Rust client core for the current /api HTTP endpoints. Rust desktop clients and Omaclipsync consume the same exported snapshot. Update server and clients together. Device identity, cursor, encryption and Rust API types are unchanged. Local tests and HTTPS interoperability passed.