chore(release): 0.3.0

Bump workspace version 0.2.0 → 0.3.0.

CHANGELOG: documents the additions in this release —
  - `journal` Cargo feature with full TraceEvent enum + machine API
  - root state targetable by chart name
  - 113 deterministic-flow tests
  - verification/ workspace member with mechanical Creusot proofs
  - docs/002 formal semantics doc
  - README "How a chart behaves" building-block section
  - mise + just tooling overhaul (set shell, set script-interpreter)

README: integrates the semantics from docs/002 as eight building-
block rules that build on each other (active path, default-descent,
event bubbling, transitions, up-transition rule, entry/exit
ordering, timer lifecycle, emit / during / termination). Adds an
explicit "what hsmc deliberately does NOT have" table with what to
use instead. New "Verification" section pointing at `just verify`.

No behavior changes for v0.1 / v0.2 charts — every existing chart
compiles unchanged.

CHANGELOG.md

@@ -4,6 +4,63 @@ All notable changes to this workspace are documented here. The format
 follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/) and
 this project adheres to [Semantic Versioning](https://semver.org/).
 
+## 0.3.0 — 2026-04-27
+
+### Added
+
+- **`journal` Cargo feature.** Records every observable atom of chart
+  execution — `Started`, `Entered`, `Exited`, `ActionInvoked`
+  (`Entry`/`Exit`/`Handler`), `DuringStarted`, `DuringCancelled`,
+  `TransitionFired`, `EventDelivered`, `EventDropped`, `EmitQueued`,
+  `EmitFailed`, `TimerArmed`, `TimerCancelled`, `TimerFired`,
+  `TerminateRequested`, `Terminated` — into a `Vec<TraceEvent>` on the
+  generated machine. Same chart + same events = byte-identical
+  journal. Public API: `journal()`, `take_journal()`, `clear_journal()`,
+  `CHART_HASH` (a stable FNV-1a fingerprint of the chart's structural
+  definition).
+- **Root state targetable by chart name.** `on(Trig) => MyChart;`
+  resolves to the root state in both `classify_target` and
+  `resolve_transitions`. From any nested state this is an
+  up-transition (root is always on the active path).
+- **113 deterministic-flow tests** (under `--features tokio,journal`)
+  comparing hand-built expected journals byte-for-byte against
+  actual, anchored to spec sections: initial entry, lateral / self /
+  up transitions, default-descent, event bubbling, timer arm /
+  cancel / fire, emit, ordering, durings, step-vs-dispatch
+  equivalence, root-targeting, `current_state()`, termination.
+- **`verification/` workspace member with Creusot proofs.** Verified
+  mirrors of the runtime `EventQueue` and `TimerTable` carry
+  `creusot-std` (Pearlite) contracts that Why3 + alt-ergo + z3
+  discharge mechanically. 14/14 VCs proven. `just verify` is
+  self-installing (mise pulls opam + the pinned nightly + Creusot's
+  canonical `INSTALL`).
+- **`docs/002. hsmc-semantics-formal.md`** — canonical, unambiguous
+  reference for chart behavior. Numbered S-rules supersede the v0.1
+  prose spec and v0.2 design-change-request.
+- **README "How a chart behaves" section** — eight building-block
+  rules that build on each other, with an explicit "what hsmc
+  deliberately does NOT have" table.
+
+### Tooling
+
+- `mise.toml` (root) declares stable Rust + components + embedded
+  targets + cargo subcommands. `verification/mise.toml` declares
+  the pinned `nightly-2025-11-13` + opam + python venv + uv.
+- `set shell` and `set script-interpreter` route every `just` recipe
+  through `mise exec` — no shebangs, no per-recipe wrappers.
+- `just verify` runs `cargo creusot prove --no-cache` so SMT
+  invocations happen on every run; `time` shows ~7s CPU on ~1.2s
+  wall = real parallel work.
+- `just mutants` runs with `--features tokio,journal` so `journal_*`
+  and `det_*` tests execute. **0 missed mutants.**
+- `just miri` excludes `hsmc-macros` (trybuild glob hits Miri's
+  isolation) and `hsmc-verification` (different pinned toolchain).
+  66 tests pass under Miri, 0 UB.
+
+### Backward compatibility
+
+Every v0.1 / v0.2 statechart compiles under v0.3 unchanged.
+
 ## 0.2.0 — 2026-04-22
 
 ### Fixed — behavior-visible (breaking)