feat(booter): complete P2P POSIX roadmap items and doc alignment

- ADRs under docs/adr/; KERNEL_CONTRACT + env appendix + handbook updates
- socketMsgSurface schema 5; replication_snapshot schema 2; syscall/example + tests
- MBR pacing docs/microbench; export mbrReadTimeoutMsForDisk; shell passthrough envs
- verify-ctx-api-feature-bits: syscall schema vs posix-compliance-matrix
- Wasm hostname import, disk.os snapshot hints, kernel-ext resolution docs
- coreutils nice + matrix/dashboard; syscalls.example ctxApiVersion 1.51.1
- Seeder kernel rsync parity; assorted booter/protocol doc fixes

docs/reference/compatibility-matrix.md

@@ -14,7 +14,7 @@ Single place to compare **protocol**, **booter `ctx` API**, **feature-bit docume
 
 ## Version artifacts
 
-**`bareOsCtxApiVersion`** (current stock: **`1.51.0`**) — Defined in [`packages/bare-os-booter/lib/bare-os-ctx-api.js`](../../packages/bare-os-booter/lib/bare-os-ctx-api.js). This is the semver string for the documented **`ctx`** contract; bump it when stable guest-visible behavior changes.
+**`bareOsCtxApiVersion`** (current stock: **`1.51.1`**) — Defined in [`packages/bare-os-booter/lib/bare-os-ctx-api.js`](../../packages/bare-os-booter/lib/bare-os-ctx-api.js). This is the semver string for the documented **`ctx`** contract; bump it when stable guest-visible behavior changes.
 
 **`BARE_OS_KERNEL_FEATURE_BITS_DOC`** (current stock: **`15`**) — Exported from [`packages/bare-os-protocol/lib/kernel-feature-bits.js`](../../packages/bare-os-protocol/lib/kernel-feature-bits.js). It versions the feature-bit documentation and related governance; keep it aligned with [`developer-guide/adr/001-kernel-feature-bits-governance.md`](../../developer-guide/adr/001-kernel-feature-bits-governance.md).
 
@@ -26,7 +26,7 @@ Single place to compare **protocol**, **booter `ctx` API**, **feature-bit docume
 
 **POSIX-like profile** — **`BARE_OS_POSIX_PROFILE_VERSION`** (**`1.0.15`**) and **`BARE_OS_POSIX_PROFILE_ID`** (**`bare-os-posix-like`**) in [`bare-os-protocol/lib/bare-os-posix-profile.js`](../../packages/bare-os-protocol/lib/bare-os-posix-profile.js). Surfaced under **`/proc/bare_os_features`** as **`capabilitySurface.posixProfile`** and in **`/proc/bare_os/syscalls.json`**.
 
-**`/proc/bare_os/syscalls.json`** — Schema **10** (see also [handbook ch.9 §2.3](../../handbook/09-posix-utilities-shell-and-vfs.md#23-pseudo-proc-sys-run-dev-and-session-tmp)) adds **`posix_fadvise`** as a simulated **`ctx.bareOsSyscall`** no-op and retains **`clock_gettime`** (REALTIME / MONOTONIC sketch); earlier schema fields remain: cooperative **`fcntl`** advisory locks (optional **`BARE_OS_POSIX_FCNTL_BLOCKING_WAIT`** for **`F_SETLKW`**-shaped waits), optional **`BARE_OS_POSIX_SOCKET_FD_BRIDGE`** **`socket`/`connect`** (**`SOCK_STREAM`** via **`bareTcp`**, **`SOCK_DGRAM`** via **`bareDgram`** when merged) with bounded **`send`/`sendmsg`/`recv`/`recvfrom`/`recvmsg`** on bridged datagram fds (**`BARE_OS_POSIX_DGRAM_RECVQ_MAX`**, **`BARE_OS_POSIX_DGRAM_RECV_BLOCK_MS_MAX`**), **`socketMsgSurface`** schema **4** (**`sendmsg`/`recvmsg`** partial on bridge; binary ancillary **`ENOTSUP`**; optional **`logicalScmRightsOnSend`** when **`BARE_OS_POSIX_SOCKET_SCM_RIGHTS`**; **`recvmsg`** **`controllen` 0**), and retains socket-family **probes** plus **`posixXsh`**. Earlier schemas added **`fdModel`**, **`signalModel`**, **`opsDetail`**, **`errnoHints`**, and **`posixProfile`**. The stock booter **caches** the JSON text until **`vfs.bareOsClearWarmReadCaches()`** / **`ctx.bareOsInvalidateWarmReadCaches()`** (same invalidation path as **`/bin`** warm cache; **`boot/init.js`** and **`lib/init/**` batch puts also invalidate). Example payload: [`kernel/etc/bare-os/syscalls.example.json`](../../kernel/etc/bare-os/syscalls.example.json); JSON Schema: [`docs/schemas/bare-os-syscalls.schema.json`](../schemas/bare-os-syscalls.schema.json).
+**`/proc/bare_os/syscalls.json`** — Schema **10** (see also [handbook ch.9 §2.3](../../handbook/09-posix-utilities-shell-and-vfs.md#23-pseudo-proc-sys-run-dev-and-session-tmp)) adds **`posix_fadvise`** as a simulated **`ctx.bareOsSyscall`** no-op and retains **`clock_gettime`** (REALTIME / MONOTONIC sketch); earlier schema fields remain: cooperative **`fcntl`** advisory locks (optional **`BARE_OS_POSIX_FCNTL_BLOCKING_WAIT`** for **`F_SETLKW`**-shaped waits), optional **`BARE_OS_POSIX_SOCKET_FD_BRIDGE`** **`socket`/`connect`** (**`SOCK_STREAM`** via **`bareTcp`**, **`SOCK_DGRAM`** via **`bareDgram`** when merged) with bounded **`send`/`sendmsg`/`recv`/`recvfrom`/`recvmsg`** on bridged datagram fds (**`BARE_OS_POSIX_DGRAM_RECVQ_MAX`**, **`BARE_OS_POSIX_DGRAM_RECV_BLOCK_MS_MAX`**), **`socketMsgSurface`** schema **5** (**`sendmsg`/`recvmsg`** partial on bridge; binary ancillary **`ENOTSUP`**; optional **`logicalScmRightsOnSend`** when **`BARE_OS_POSIX_SOCKET_SCM_RIGHTS`**; **`recvmsg`** **`controllen` 0**), and retains socket-family **probes** plus **`posixXsh`**. Earlier schemas added **`fdModel`**, **`signalModel`**, **`opsDetail`**, **`errnoHints`**, and **`posixProfile`**. The stock booter **caches** the JSON text until **`vfs.bareOsClearWarmReadCaches()`** / **`ctx.bareOsInvalidateWarmReadCaches()`** (same invalidation path as **`/bin`** warm cache; **`boot/init.js`** and **`lib/init/**` batch puts also invalidate). Example payload: [`kernel/etc/bare-os/syscalls.example.json`](../../kernel/etc/bare-os/syscalls.example.json); JSON Schema: [`docs/schemas/bare-os-syscalls.schema.json`](../schemas/bare-os-syscalls.schema.json).
 
 **`/proc/bare_os/process_table.json`** — Schema **7** (see **`fdModel.processTableSchema`** inside **`syscalls.json`** and [handbook ch.9 §2.3](../../handbook/09-posix-utilities-shell-and-vfs.md#23-pseudo-proc-sys-run-dev-and-session-tmp)); documents logical jobs, PGID/SID-style fields, initd binding, and signal routing.