feat(arduino): support XIAO firmware and BLE input

[wingwogus]

Summary

• add automatic XIAO nRF52840 Sense BLE Nordic UART Service discovery and route P/R input through the existing gesture path
• select the correct bootloader transport from registry FQBN: retain STK500v1 for Uno and use Seeed serial DFU for XIAO
• move the board installer from the stale hana-registry endpoint to Hana Cloud and add exact XIAO USB-ID regression coverage
• make onboarding copy board-neutral so it describes registry-supported hardware rather than Uno only

Dependency

Requires the registry source PR to publish its generated manifest and verified HEX first: dev-five-git/hana-cloud#6

Hardware evidence

• flashed the XIAO through serial DFU; post-flash USB handshake returned HANBEON_UNO_V1
• with XIAO powered from a charger and USB data disconnected, app found NUS service 6e400001-b5a3-f393-e0a9-e50e24dcca9e and logged repeated BLE Pressed / Released events

Verification

• cargo fmt --check
• cargo test --lib — 180 passed
• cargo clippy --all-targets -- -D warnings
• bun test apps/desktop/src/__tests__/arduino-firmware.browser.test.ts apps/desktop/src/__tests__/arduino-setup.browser.test.tsx — 27 passed

The full bun test suite runs 70 tests successfully but returns exit 1 after LCOV reporting without an error; this is a pre-existing test runner/reporting issue. Pre-commit typecheck and oxlint completed successfully (with existing non-blocking warnings in ArduinoSetup.tsx).