feat: upgrade all dependencies to latest versions

Major version bumps:
- defmt 0.3 → 1.0
- esp-hal 0.22 → 1.0 (full API migration)
- esp-hal-embassy 0.5 → esp-rtos 0.2 (replacement crate)
- esp-backtrace 0.14 → 0.18
- esp-println 0.12 → 0.16
- embassy-nrf 0.2 → 0.10
- embassy-embedded-hal 0.2 → 0.6
- embassy-sync 0.6 → 0.8
- embassy-time 0.3 → 0.5
- embassy-usb 0.3 → 0.6
- embassy-usb-driver 0.1 → 0.2
- embedded-io-async 0.6 → 0.7
- heapless 0.8 → 0.9
- panic-probe 0.3 → 1.0
- minijinja 2.0 → 2.18
- owo-colors 4.0 → 4.3

embassy-executor stays at 0.9 (latest with Xtensa support via esp-rtos).
Updated ESP toolchain from 1.82 to 1.93.

Justfile

@@ -113,7 +113,7 @@ _require_esp_toolchain:
         echo "error: ESP toolchain not found" >&2; \
         echo "  install:" >&2; \
         echo "    cargo install espup" >&2; \
-        echo "    espup install --toolchain-version 1.82.0.3" >&2; \
+        echo "    espup install" >&2; \
         exit 1; \
     fi