Register SkillDefinitionCatalog from content/skills with JsonSchema.Net validation
mirroring validate_content.py and the prototype Slice 1 gate. Resolve paths via
Content:SkillsDirectory or discovery from AppContext.BaseDirectory. Eager-load
after WebApplication build so bad catalogs block startup. Add unit and host
tests, pin test factories to repo skills, document config in server/README, add
manual QA checklist, and extend Bruno GET /health smoke tests.
VinPropane