- Fix swapped command IDs: attach_backing was 0x0104 (FLUSH),
resource_flush was 0x0106 (ATTACH_BACKING). Now correct.
- Increase process stack from 4 pages (16 KB) to 16 pages (64 KB)
to prevent stack overflow in display process.
- Restructure display-qemu to avoid MockFramebuffer's 32 KB array
inflating the VirtIO path's stack frame.
- Wire snake app to render through display server via IPC instead
of UART escape codes. Uses existing renderer.rs pixel renderer.
- Init now delegates display endpoint to snake process.
