feat(kernel): giant-phase boot hooks, proc snapshot, and kernel UX tools

- Add BARE_OS_BOOT_SAFE_MODE, BOOT_TRANSACTION_JOURNAL, BOOT_CHECKPOINT in
  stock kernel; kernel.ext.d requires/after/before ordering; boot-ready
  subsystems.kernel.giantPhase adjunct
- Expose /proc/bare_os/giant_phase_program.json via bare-os-giant-phase;
  wire VFS, baretop snapshot, and ctx batch read
- Add /bin/kernel-doctor and /bin/kernel-explain; verify-giant-phase-doc in
  pretest; giant-phase-benchmark-harness stub
- Bump bareOsCtxApiVersion to 1.23.0; sync seeder kernel/init.js and runtime
  caps; extend booter tests for proc listing and safe mode

Docs: giant-phase-kernel-program.md, feature-roadmap, kernel-extensions,
compatibility-matrix, environment appendix, handbook 06/11, developer
guide, users-manual 07, scripts README; booter CHANGELOG

developer-guide/README.md

@@ -50,6 +50,7 @@ This project is **experimental research software**. APIs described here follow t
 - **[13 — Privacy, telemetry, and PII](13-privacy-telemetry-pii.md)** — Scrub lists for NDJSON / OTel mirrors; non-secret posture.
 - **[Node → Bare module map](node-to-bare-modules.md)** — Guest-safe replacements for **`node:*`** built-ins (**`bare-crypto`**, **`bare-module`**, …).
 - **[bare-boot vs kernel phases](bare-boot-kernel-phase-alignment.md)** — Conceptual map: Holepunch **`bare-boot`** stages vs stock **`kernel/init.js`**.
+- **[Giant phase kernel program (100 items)](giant-phase-kernel-program.md)** — Mega-kernel governance, boot hooks, proc snapshot, Bare stack pointers.
 
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