refactor(radio): chart-first restructure on hsmc 0.3 + soak hardening

Migrate from hsmc 0.2 (local-patched) to hsmc 0.3.0 (crates.io, with
embassy + trace-defmt features). Restructure radio chart and bundle
several adjacent stability changes that need to land together for
soak runs.

Radio chart:
- Booting (default, no handlers) -> Operational (default Unconfigured;
  super-state owning CmdPing/CmdGetInfo/Reset/WedgeDetected handlers
  + Recovering + CheckRecoveryBudget) -> Dead (terminal).
- Cold init's during is structurally un-cancellable.
- radio_task is a 30-line shim that panics if run() returns (chart is
  non-terminating).
- Internal queue capacity bumped 8 -> 32 to cover action-emit bursts.

Host chart:
- Connected splits into WaitingForFirstFrame (default, no timer) +
  Active (chart-owned 1s inactivity timer via on(after) + self-
  transition on FrameReceived). Manual Timer::after + last_frame_at
  removed.

Soak hardening:
- ld/nrf52840-memory.x: app start 0x1000 -> 0x26000 to leave the
  factory s140 SoftDevice dormant in flash.
- hal/nrf52840.rs: dump POWER.RESETREAS on boot -- WARN on DOG/LOCKUP,
  INFO on RESETPIN/SREQ/wake-from-OFF.
- host/usb.rs: read_packet errors discriminated -- Disabled is debug
  (normal during USB enum), BufferOverflow stays warn.
- COBS encode warns now carry type/tag/payload-length for diagnosis.
- RADIO_THROTTLED static initializes to true (no proof of host drain
  at boot).
- driver/sh1106.rs: init retries 3x with 100ms backoff (intermittent
  first-write race on power-up).
- Cargo.toml: unexpected_cfgs allowlist for hsmc's journal/trace-*
  features.

docs/semtech_lora_cad_lbt_guidebook.md: vendor the Semtech CAD/LBT
reference for offline lookup.

src/main.rs

@@ -84,6 +84,15 @@ cfg_if::cfg_if! {
 #[cfg(not(test))]
 async fn run(spawner: Spawner) {
     let board = <board::Board as LoRaBoard>::init();
+
+    // Read + log + clear POWER.RESETREAS before any other boot output so
+    // the cause of the *previous* reset (if any) lands at the very top
+    // of the RTT log. Critical for soak-debugging silent crash-reboots:
+    // a self-rebooting firmware otherwise looks like the log just
+    // restarted with no explanation. nRF52840-only.
+    #[cfg(any(feature = "rak_wisblock_4631", feature = "wio_tracker_l1"))]
+    crate::hal::nrf52840::dump_reset_reason();
+
     let parts = board.into_parts();
 
     // Build the GET_INFO struct once at boot. This is the authoritative