fix(syscall): synchronize Landlock global state

[kernalix7]

Summary

Replace unsynchronized mutable Landlock registries with one spinlock-protected state object, eliminating parallel host-test data races and undefined behavior.

Changes

• move rulesets and thread restrictions into SpinLock<LandlockState>
• keep create, add, restrict, check, close, and query operations within one guarded state snapshot
• serialize stateful Landlock tests and reset shared state between cases
• add a scoped multithreaded create/add/restrict/check regression test

Testing

• cargo fmt --all -- --check
• cargo clippy --workspace -- -D warnings
• cargo build --workspace
• focused Landlock suite repeated 20 times under default parallelism: 860/860 passed
• strict-provenance/preemptive Miri: 43/43 Landlock tests passed
• bash scripts/run-tests.sh: 4,620 passed, 0 skipped
• bash scripts/run-qemu-test.sh: x86_64, aarch64, and riscv64 passed

Checklist

• Formatting, Clippy, and workspace build pass
• Public APIs remain documented and unchanged
• No new unsafe blocks or external dependencies
• No new files require license headers
• Documentation changes are not required for this internal synchronization fix
• No hardcoded paths, credentials, or personal information