The detail page rendered an empty <PageHero /> (blank gradient band) with the
real title buried in a card lower down (Phase 0 finding).
- Populate the detail PageHero with the project category (badge), title and
summary, so the top of the page is a proper header.
- Slim the in-content ProjectHeader to back-link + meta chips + preview button,
removing the now-duplicated title and summary. Applies across all three
detail templates (grid/story/case-study).
Verified: eslint clean, no new type errors.