init() ran at line 514 (document.body exists at @run-at document-idle),
but buildUI() reads the TEMPLATE/CSS consts declared lower in the IIFE.
Accessing them before initialization threw ReferenceError: Cannot access
'CSS' before initialization, so the script died before mounting the FAB
and no UI appeared in Cromite. Move the boot invocation to the end of the
IIFE, after both consts are initialized.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>