Add platform-aware IPC transport layer for the launcher protocol:
- transport module: send_request_sync() auto-selects doors (illumos)
or Unix sockets (Linux) at compile time
- doors_transport: uses doors::Client for high-speed synchronous RPC,
gated behind cfg(target_os = "illumos") + "doors" feature flag
- unix_transport: blocking Unix socket client for all platforms
Simplify client binaries to use the sync transport:
- wradm: drops tokio dependency entirely, now fully synchronous
- wrlogin: drops tokio dependency, uses sync transport
- wrsessd: uses shared default_ipc_path() for consistency
The doors crate (0.8.1) is an optional illumos-only dependency.
On Linux, all code compiles and tests pass with Unix socket transport.
Encoder: xor_diff + encode_region (per damage rectangle).
Decoder: apply_region (decompress + XOR apply to framebuffer).
Both live in wayray-protocol::encoding for shared access.
14 tests including 3 end-to-end round-trip integration tests.
Message types for control, display, and input channels with serde
derives. Length-prefixed postcard codec with encode/decode/framing.
Seven round-trip tests covering all message types and edge cases.
