chore(cv): update EN CV to the research-scientist version (6pp)

Replaces res/cv/CV_Linlin_Jia_en.pdf (was 41KB) with the new 207KB research_scientist
build (PDF v1.5, 6 pages, Title "Linlin Jia – Ph.D."). Same filename, so every "my cv"
link (About headline en/fr/de + JSON-LD) picks it up automatically.

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

Author: jajupmochi