seedGuide() ran in onMount via the 'else' branch while template was still null during the async
fetch, creating 5 example shapes (Q1 start/end, part, response, context) that flashed on screen
until the real template + PDF loaded. Only seed the guide for a genuinely-empty template after load.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>