feat: hsmc statechart rewrite with wake/run/shutdown animations

- Pull the entire device lifecycle into a single hsmc 0.5.1 statechart;
  remove JIGGLE_FLAG, the Phase enum, the imperative main loop, and the
  separate led_task.
- Add wake-up (horizontal shake), running (3 fast circles), and
  pre-shutdown (inward spiral) mouse animations as during: activities.
- Tighten reset → wake-shake latency from ~2s to ~240ms; HID poll_ms
  60 → 8 so the host actually samples animation frames.
- Set RUN_DURATION = 3h50m, the math-optimum under the user's workday
  distribution for "screen sleeps during lunch on most days."

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,56 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `hsmc` 0.5.1 statechart drives the entire device lifecycle. The control
+  flow (boot → wake-up animation → settle → running animation → active
+  jiggle/flash → end-of-day shutdown spiral → power-down) is expressed
+  declaratively in one `statechart!` block; no more atomic flags, no more
+  per-tick `Phase` enum, no hand-rolled main loop.
+- Mouse animations driven by the chart's `during:` activities:
+  - **Wake-up** (`WakingDisplay`): 10 frantic horizontal sin-shaped sweeps
+    (~12 Hz, ±60 px, ~640 ms) — simulates "shake the mouse to wake the
+    display."
+  - **Running** (`ShowingRunning`): 3 quick clockwise circles
+    (radius 40 px, ~600 ms) — universal "spinner / in progress" cue.
+  - **Pre-shutdown** (`Ending → ShutdownAnim`): inward spiral 50 → 5 px
+    over 3 turns (~2 s), 30 s before lifetime end — cursor visibly winds
+    down.
+- 2 s `Settling` state between wake-up and running animations so the
+  display has time to come out of sleep before the spinner draws.
+- All animations carry sub-pixel residue forward across `i8` HID delta
+  reports so the rendered shape matches the intended geometry rather than
+  losing ~half its motion to truncation.
+
+### Changed
+
+- **`RUN_DURATION` from 8 hours to 3 h 50 m**. Math-optimal under the
+  user's workday distribution (start `triangular(8.0, mode=8.5, 9.5)`,
+  lunch 12:00–13:00, end `triangular(16.0, mode=17.5, 19.0)`) for "screen
+  goes to sleep during the lunch hour on most days." See
+  `/tmp/jiggly_runtime_v3.py` for the simulation.
+- HID `poll_ms` 60 → 8 (125 Hz). At the previous 60 ms poll the host
+  was discarding ~7 of every 8 animation frames the firmware emitted.
+- Boot LED `R→G→B` step 180 ms → 60 ms; 1.5 s pre-animation USB-settle
+  delay removed. Reset → wake-shake latency dropped from ~2 s to ~240 ms.
+- Watchdog feeding moved out of the imperative main loop into its own
+  `#[embassy_executor::task]`; the chart owns user-visible state, the
+  watchdog task owns the periodic kick.
+- USB descriptor unchanged (still spoofs Logitech G502 VID `0x046d` /
+  PID `0xc07d`).
+
+### Removed
+
+- `JIGGLE_FLAG: AtomicBool` and all `swap`/`store` calls.
+- `Phase` enum and the per-tick `phase_for(remaining)` switch — the
+  breathing color is now read directly from elapsed time inside the
+  `breathe_color` `during:`.
+- `led_task` and `sleep_chunked` helper — both subsumed by the chart.
+- `RUN_DURATION = Duration::from_secs(8 * 60 * 60)` and similar
+  raw-integer-millisecond constants. All timing is now `Duration`-typed
+  with named constructors (`from_hours`, `from_mins`, `from_millis`).
+
 ## [0.1.0] - 2026-04-27
 
 ### Added