Editor Benchmarks Neutral Registry + Fixtures

Goal

Implement a benchmark-owned neutral protocol registry and fixture layer in /Users/zbeyens/git/editor-benchmarks.

Scope

• stop making the app's truth depend directly on Plate docs
• seed neutral registry data from current Plate behavior work
• add canonical fixture metadata for benchmark lanes
• wire the app to load and surface the new layer

Verification

• npm run build:web
• npx eslint on touched files
• browser screenshot on http://127.0.0.1:3023