Move Post/Author/Tag/PostAuthor/PostTag/PostUser models from
shared/models/ghost_content.py to blog/models/content.py so blog-domain
models no longer live in the shared layer. Replace the shared
SqlBlogService + BlogService protocol with a blog-local singleton
(blog_service), and switch entry_associations.py from direct DB access
to HTTP fetch_data("blog", "post-by-id") to respect the inter-service
boundary.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
entry_associations only uses HTTP fetch_data/call_action, no direct DB.
Events app imported it via ..post.services which doesn't exist in events.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
