feat(state): add reversible execution and memory generations

[appcypher]

TL;DR

Add reversible, generation-scoped execution control and full or incremental guest-memory state capture across KVM, HVF, and WHP.

Description

• expose typed pause tokens that bind execution, memory access, and captured state to one pause generation
• capture and restore versioned architecture-specific vCPU and VM execution envelopes
• capture complete memory generations and retained-baseline deltas with explicit dirty-coverage confirmation and safe full fallback
• freeze device memory access before final dirty capture so asynchronous device writes cannot escape the generation boundary
• preserve sparse ranges and stream eager restore without requiring an in-memory copy of the guest address space
• make pause and resume reversible across all supported hypervisor backends, with explicit stale-token and invalid-transition errors

Test Plan

• cargo fmt --all -- --check
• cargo test --locked --offline -p msb_krun -p msb_krun_vmm -p msb_krun_devices --lib (144 passed)
• Live macOS ARM64/HVF: repeated pause/resume, full capture, retained-baseline incremental capture, restore, and event-driven running-state observation
• Live Linux x86_64/KVM: repeated pause/resume, full capture, sparse dirty generation, restore, and invalid-transition rejection