Use the LGMP input queue when the host advertises transport input,
while preserving SPICE fallback through the existing input abstraction.
Claim input lazily, publish ordered full-state keyboard and mouse
reports without blocking rendering, and keep the owner lease alive.
Reserve queue capacity for discrete transitions, coalesce only motion
under pressure, and release ownership safely during idle and disconnect.
Keep the Linux-to-HID map in the client and update LGMP to the
nonblocking data-send API required by the input worker.
Move shared-memory ownership, LGMP session handling, queue access, and
DMA setup behind a transport interface. The LGMP backend preserves the
existing zero-copy frame and DMA paths while owning its lgmp:* options.
Expose the initialized EGL context through a versioned renderer interop
record for future accelerated decode backends. Add an LGMP-independent,
deterministic test transport for graphics-pipeline validation.
