Adds writing, portfolio-entry, bookshelf-entry, and curated-blog
collection types with attributes mirroring the TOML frontmatter
fields in content/README.md exactly, so the future sync provider has
a direct field mapping. draftAndPublish is disabled on all four since
our own `draft` boolean (synced to the file) is the source of publish
state, not Strapi's built-in workflow. Verified Strapi boots and
registers all four REST routes (api/writings, api/portfolio-entries,
api/bookshelf-entries, api/curated-blogs).
