Initial project setup: README, Cargo.toml, and CLI scaffolding

- Add README with project overview, architecture, and roadmap
- Set up Rust project with clap, toml, serde, tracing dependencies
- Scaffold CLI with 6 commands (init, validate, diff, check, apply, rollback)
- Create module structure for config, state, planner, executor, jail, vm, zfs
- Create test directory structure for unit/integration/idempotency tests

src/commands/mod.rs

@@ -0,0 +1,8 @@
+pub mod commands {
+    pub mod init {}
+    pub mod validate {}
+    pub mod diff {}
+    pub mod check {}
+    pub mod apply {}
+    pub mod rollback {}
+}