Publish full "Evaluating PII Detection Models" blog post

Replace the Medium blurb with the complete article: all sections,
code blocks (canonical hierarchy, clinical record, call-center
transcript), the two data tables reproduced as native markdown, and
the three graphics (hero, IoU equation, pipeline) committed under
src/assets/blog/ and served through Astro image optimization.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: omri374