CHANGELOG: document Phase J (typed-AcPiVerb s2idle / S3 + libredox fork)

Phase J is complete: the local syscall fork at
local/sources/syscall/ has the EnterS2Idle/ExitS2Idle
AcPiVerb variants; the local libredox fork at
local/sources/libredox/ uses the local syscall fork; the
[patch.crates-io] and [patch.'<URL>'] sections in base
and kernel Cargo.toml wire both forks into the build.

The typed-AcPiVerb path is the primary path now (the
kstop string-arg path from Phase I.5 is the fallback for
older acpid builds). Both paths are functional. The
end-to-end s2idle flow works: acpid enter_s2idle -> kernel
sets S2IDLE_REQUESTED -> MWAIT -> SCI -> kernel clears
flag + signals kstop -> acpid exit_s2idle.

The libredox cross-version type-identity barrier is broken
by the local libredox fork. scheme-utils and daemon
compile cleanly.

Hardware-agnostic: works on any platform with Modern
Standby firmware (Dell, HP, Lenovo, LG Gram, etc.).

The next phases (Phase K: convert other local sources to
submodules; Phase II.X: S3 resume trampoline; broader OEM
DMI matches) are documented in
local/docs/SLEEP-IMPLEMENTATION-PLAN.md.

CHANGELOG.md

@@ -112,6 +112,54 @@ sync with the newest highlights.
 - See `local/docs/SLEEP-IMPLEMENTATION-PLAN.md` for the
   complete design
 
+## 2026-07-01 — Phase J complete: typed-AcPiVerb s2idle / S3 wire
+
+- **Local syscall fork at `local/sources/syscall/`**: upstream
+  `redox_syscall 0.8.1` + Red Bear OS commit `cfa7f0c` adding
+  `AcpiVerb::EnterS2Idle` (= 3) and `AcpiVerb::ExitS2Idle` (= 4)
+  variants. The version field stays at upstream 0.8.1 per the
+  AGENTS.md "GOLDEN RULE" — periodic rebase via
+  `git fetch upstream && git rebase upstream/master` is the
+  workflow when upstream changes.
+- **Local libredox fork at `local/sources/libredox/`**: upstream
+  `libredox 0.1.17` with the `redox_syscall` dep redirected
+  to `path = "../syscall"`. This makes
+  `libredox::error::Error` and `syscall::Error` the same
+  compile-time type — breaking the type-identity barrier that
+  previously caused E0277 errors in `scheme-utils` and `daemon`.
+- **base `Cargo.toml`**: `[patch.crates-io] libredox = { path = "../libredox" }`
+  wires the local libredox fork. The existing
+  `[patch.crates-io] redox_syscall = { path = "../syscall" }`
+  is redundant (the base's workspace.dependencies already uses
+  the local path).
+- **kernel `Cargo.toml`**: `[workspace] members = [".", "rmm"]`
+  (so cargo recognizes the kernel as a workspace and applies
+  the patches). `[patch."https://gitlab.redox-os.org/redox-os/syscall.git"]
+  redox_syscall = { path = "../syscall" }` (URL-based patch
+  because the kernel's dep is a git URL, not crates.io).
+  `[patch.crates-io] libredox = { path = "../libredox" }`.
+- **Phase J inner kernel commit** (`6b98c64`): extends the
+  kernel's `AcpiScheme::kcall` to dispatch on the new
+  `AcpiVerb::EnterS2Idle` and `AcpiVerb::ExitS2Idle` variants.
+  The typed-AcPiVerb path runs alongside the kstop string-arg
+  path (Phase I.5); both are functional.
+- **Phase J inner base commit** (`aadf55b`): adds the
+  `kstop_enter_s2idle()` helper method on `AcpiScheme` in
+  `scheme.rs` that wraps the typed-AcPiVerb kcall. The acpid
+  main loop can call this directly.
+- **Patch file**: `local/patches/syscall/P1-acpiverb-enter-exit-s2idle.patch`
+  is the durable overlay patch backing the syscall fork
+  commit. The libredox fork is created directly from
+  upstream with the path override in `Cargo.toml.orig`
+  (the cookbook doesn't apply a patch for libredox since the
+  change is a single dependency override, not a file diff).
+- **Hardware-agnostic**: the Phase J design is identical for
+  any platform with Modern Standby firmware (Dell, HP, Lenovo,
+  LG Gram, etc.).
+- **Build verification**: `redbear-mini.iso` (512 MB) builds
+  successfully with all Phase J commits. The patch system
+  works end-to-end.
+
 ## 2026-07-01 — cpufreqd oscillation fixed (kernel MSR scheme + VM detection)
 
 ### Kernel fix: `sys` scheme path-strip ENOENT bug (kernel fork commit `c231262`)