feat: extract reversible-core crate from januskey

Extract the core reversibility types into a shared library crate that
ochrance and valence-shell can depend on, while keeping the CLI in
januskey-cli.

reversible-core provides:
- ContentHash + ContentStore (SHA256 content-addressed storage)
- OperationMetadata + MetadataStore (append-only operation log)
- Transaction + TransactionManager (begin/commit/rollback)
- ReversibleExecutor trait (Rust mirror of ochrance's VerifiedSubsystem)
- ManifestEmitter (A2ML manifest generation for ochrance verification)
- OperationType with formal inverse mapping (per absolute-zero CNO theory)

Lineage: maa-framework → absolute-zero → januskey → {ochrance, valence-shell, aletheia}

44 tests passing across both crates.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

Cargo.lock

@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: PMPL-1.0-or-later
+# SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell
+
+[workspace]
+members = ["crates/reversible-core", "crates/januskey-cli"]
+resolver = "2"
+
+[workspace.package]
+edition = "2021"
+license = "MIT OR PMPL-1.0-or-later"
+repository = "https://github.com/hyperpolymath/januskey"
+authors = ["Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>"]
+
+[profile.release]
+lto = true
+codegen-units = 1
+opt-level = 3

Cargo.toml

@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: PMPL-1.0-or-later
+# SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell
+
+[package]
+name = "januskey"
+version = "1.0.0"
+description = "Provably reversible file operations through Maximal Principle Reduction"
+keywords = ["reversible", "filesystem", "transactions", "undo", "backup"]
+categories = ["command-line-utilities", "filesystem"]
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+authors.workspace = true
+
+[dependencies]
+reversible-core = { path = "../reversible-core" }
+clap = { version = "4", features = ["derive"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+sha2 = "0.10"
+chrono = { version = "0.4", features = ["serde"] }
+uuid = { version = "1", features = ["v4", "serde"] }
+thiserror = "1"
+anyhow = "1"
+hex = "0.4"
+flate2 = "1"
+dirs = "5"
+walkdir = "2"
+colored = "2"
+dialoguer = "0.11"
+indicatif = "0.17"
+glob = "0.3"
+whoami = "1"
+
+# Key management dependencies
+aes-gcm = "0.10"
+argon2 = "0.5"
+rand = "0.8"
+zeroize = { version = "1", features = ["derive"] }
+subtle = "2"
+base64 = "0.22"
+
+[dev-dependencies]
+tempfile = "3"
+assert_cmd = "2"
+predicates = "3"
+
+[[bin]]
+name = "jk"
+path = "src/main.rs"
+
+[[bin]]
+name = "jk-keys"
+path = "src/keys_cli.rs"