Fix architecture SVG viewBox to crop to actual content area

The draw.io export placed content at x=3899-4720, y=2211-2846 but
viewBox started at 0,0 causing the diagram to render as a tiny image
in the bottom-right corner with mostly whitespace.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: haowu77