OpenTag Station v1.0.1-beta.2

PRE-RELEASE. Not for general use. This build is for testing and may lose data or
need a USB reflash to recover. It is not offered by the USB installer. If you want a
working station, install the latest stable release instead.

To test it anyway, upload opentag-station-1.0.1-beta.2-application.bin in the station's
web page under Settings → Update. Back up your settings first.

Pre-release for testers. Internal cleanup; nothing changes for a user.

• Removed code that only the tests used: the first-generation tag writer, the SPI bring-up for
  the NFC chip, the shared-I2C diagnostic, an unused tag-presence state machine, the runtime task
  table and the event queue. Their tests went with them. The code that reads and writes tags on a
  station is unchanged.
• The tag-protocol check (check_production_nfc.py) now fails if any of the removed files comes
  back.
• Removed two unused fields (boot_started_ms_, the Wi-Fi scan list in the diagnostics snapshot).
• Documented that the reader driver has no host test.