feat: POSIX/P2P roadmap — multisig shape, socket bridge, bin index, docs

- Unify pear.multisig.json validation via bare-os-protocol + kernel boot fragment
- Socket bridge: SCM_RIGHTS path, ancillary handling, TCP half-close/shutdown how,
  connect tcpRecvQueue + poll/recv EOF and EPIPE-shaped errors
- Bin manifest / Hyperbee hints schema 2 + namesDigest; batch-write invalidation
- Host booter structured logging; BOOT_PERF_DETAIL bare_stdlib_merge_ns timing
- Wasm kernel optional syscall imports; security_posture rotation hints schema 2
- Shell errexit inside compound bodies; expand getconf/_SC_* and bareOsGetconfSysconf
- Subprocess bridge snapshot timeoutPolicy; blind-relay protomux backpressure tests
- Pear updater minimal delegate example + verify-pear scan; holepunch drift repos
- Refresh handbook, kernel-image, syscall-socket-contract, posix matrix, PEAR-RUN

Rebuild coreutils/bundles; bundle kernel; keep seeder/kernel parity.

kernel/lib/boot/00-pear-multisig-shape.js

@@ -0,0 +1,14 @@
+/**
+ * Keep algorithm in sync with `packages/bare-os-protocol/lib/bare-os-pear-multisig-shape.js`
+ * (`pearMultisigShapeOk`). Kernel bundle cannot import npm packages.
+ * @param {unknown} parsed
+ * @returns {boolean}
+ */
+function bareOsPearMultisigShapeOk(parsed) {
+  if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) return false
+  const signers = /** @type {{ signers?: unknown }} */ (parsed).signers
+  const quorum = /** @type {{ quorum?: unknown }} */ (parsed).quorum
+  if (!Array.isArray(signers) || typeof quorum !== 'number') return false
+  if (quorum < 1 || quorum > signers.length) return false
+  return true
+}