feat: POSIX/Holepunch plan — proc contracts, shell, vault audit, docs, tests

- Docs: kernel-program truth, PLACEHOLDER_BASELINE, POSIX_DECLARED_PROFILE,
  env appendix (BARE_OS_SHELL_PIPEFAIL, BARE_OS_WASM_KERNEL), package-bare-os-booter
- Booter: syscalls.json fd model, process_table exitStatusModel, shell pipeline
  exit status + kernel-runner script-error path, mirror mounts test + handbook
- Seeder: corestore_snapshot proc alignment test; hyperswarm ^4.17.0; kernel mirror sync
- Vault: vault_save audit after saveVaultToDrive; split bare-os-vault-rotation-audit.js
- Contract: protomux/hyperswarm lock fixture + test; IPC stats ipcBackpressure test
- Coreutils: XCU tests, bare-cron man seed, ACL/xattr metadata path test
- Tooling: kernel-microbench + release-gate fixture doc; ADR 002 WASM compile hook
- Changelog/ctx d.ts and dependency/lockfile updates as needed

packages/bare-os-booter/fixtures/protomux-hyperswarm-lock.json

@@ -0,0 +1,6 @@
+{
+  "schema": 1,
+  "note": "Pinned resolved versions from the repo root package-lock.json (node_modules/*). Bump when intentionally upgrading Protomux/Hyperswarm.",
+  "protomux": "3.10.1",
+  "hyperswarm": "4.17.0"
+}