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

scripts/verify-ctx-api-feature-bits.mjs

@@ -23,6 +23,14 @@ const contractPath = path.join(
   root,
   'packages/bare-os-protocol/lib/stock-booter-capability-contract.json'
 )
+const posixMatrixPath = path.join(
+  root,
+  'docs/reference/posix-compliance-matrix.json'
+)
+const syscallsProcPath = path.join(
+  root,
+  'packages/bare-os-booter/lib/bare-os-syscalls-proc-json.js'
+)
 
 function read(p) {
   return fs.readFileSync(p, 'utf8')
@@ -120,6 +128,21 @@ function main() {
     process.exit(1)
   }
 
+  const matrix = JSON.parse(fs.readFileSync(posixMatrixPath, 'utf8'))
+  const matSch = matrix.synthetic_proc?.syscalls_json_schema
+  const procTxt = read(syscallsProcPath)
+  const procSch = procTxt.match(/schemaVersion:\s*(\d+)/)
+  const procVer = procSch ? Number.parseInt(procSch[1], 10) : NaN
+  if (!Number.isFinite(matSch) || !Number.isFinite(procVer) || matSch !== procVer) {
+    console.error(
+      'verify-ctx-api-feature-bits: posix-compliance-matrix synthetic_proc.syscalls_json_schema',
+      matSch,
+      'must match bare-os-syscalls-proc-json schemaVersion',
+      procVer
+    )
+    process.exit(1)
+  }
+
   console.log(
     'verify-ctx-api-feature-bits:',
     'ctx',