Remove <esp-web-install-button> and all shadow DOM polling hacks.
Use esptool-js (vendored as dashboard/js/esptool-bundle.js) via dynamic
import to flash directly. Flash starts automatically when step 3 loads —
no button click required. Progress shown inline. On failure, shows
BOOT+RST instructions and a retry button.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
