initial commit: hsmc v0.2 with during: activities

Hierarchical statechart codegen for Rust with:
- during: activities for state-scoped concurrent I/O
- field-list borrowing (split-borrow inside the run loop)
- embassy-first async with tokio support
- STATE_CHART const for tooling/inspection
- examples: microwave, microwave_tui, embassy_full, during_radio

hsmc-macros/tests/ui/t9_1_duplicate_transition.stderr

@@ -0,0 +1,25 @@
+error: duplicate transition on trigger `Go` in state `Red`
+  --> tests/ui/t9_1_duplicate_transition.rs:15:12
+   |
+15 |         on(Go) => Yellow;
+   |            ^^
+
+error[E0405]: cannot find trait `MActions` in this scope
+  --> tests/ui/t9_1_duplicate_transition.rs:22:6
+   |
+22 | impl MActions for MActionContext<'_> {
+   |      ^^^^^^^^ not found in this scope
+
+error[E0425]: cannot find type `MActionContext` in this scope
+  --> tests/ui/t9_1_duplicate_transition.rs:22:19
+   |
+22 | impl MActions for MActionContext<'_> {
+   |                   ^^^^^^^^^^^^^^ not found in this scope
+
+warning: unused import: `Duration`
+ --> tests/ui/t9_1_duplicate_transition.rs:1:24
+  |
+1 | use hsmc::{statechart, Duration};
+  |                        ^^^^^^^^
+  |
+  = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default