Complete x86_64 full platform service parity

[Pummelchen]

Objective

Run the same core XAIOS platform-service contract under x86_64 QEMU that currently executes under AArch64 QEMU. This is an implementation issue, not a marker-only parity claim.

Current verified boundary

x86_64 currently boots through UEFI, starts all MADT-discovered APs, dispatches IPI work, enters ring 3, saves runtime-sized extended state, parses ACPI topology, performs modern VirtIO block DMA with MSI-X completion, and transmits a VirtIO network frame. The emitted contract deliberately reports userspace=0 networking=0 ai_cell=0 security=0 telemetry=0.

Acceptance criteria

• Replace the standalone early-bring-up ownership boundary with architecture services that can host the common kernel initialization path
• Port the complete EL0 process, syscall, scheduler, and create/join/cancel/exit thread ABI
• Build and load the real x86_64 init/userspace image rather than synthetic ring-3 canaries
• Implement receive-side VirtIO networking and run TCP, UDP, DNS, SSH, SFTP, and xaiosctl paths
• Mount initfs, persistence, system, ModelFS, and storage administration paths; execute x86 NVMe I/O
• Integrate capabilities, sandbox/security, updates, AI Cell lifecycle, and telemetry
• Add architecture-specific smoke, network, storage, security, and aggregate parity gates
• Make the x86 contract report readiness only after the same externally observable service gates pass
• Do not satisfy any criterion with serial markers that lack executing behavior

Validation

• make compile-check
• make hosted-sanitizer-test
• make qemu-x86_64-platform-matrix
• x86-specific userspace/network/storage/security suites
• make qemu-core-os-rc

QEMU is correctness and ABI evidence only. Physical Intel and Xeon validation remains separately tracked.