feat(blog): add blog app with loaders and commerce factory

[guitavano]

Summary

• Create reusable blog/ app for TanStack Start sites with types, CMS record access, post filtering/sorting/pagination, and 8 data loaders
• Add createBlogCommerceLoaders() factory following the same pattern as createVtexCommerceLoaders()
• Register blog app in registry.ts and add ./blog exports to package.json

Test plan

• Verify createBlogCommerceLoaders() registers all expected loader keys
• Test getRecordsByPath reads blog collections from CMS blocks
• Test BlogPostItem loader resolves a post by slug
• Test BlogpostListing loader with category/search/sort filtering
• Verify npm run build passes with no type errors

🤖 Generated with Claude Code

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Summary by cubic

Adds a reusable blog app with CMS-backed types, sorting/filtering/pagination utils, and eight loaders (post page, single post, listings, related posts, categories, authors). Registers deco-blog, exports ./blog entry points, provides a createBlogLoaders() factory (alias createBlogCommerceLoaders), and renames the internal loader map to loaderMap.ts. Adds unit tests for core utilities, CMS records access, loaders, and the module.

• New Features

  • getRecordsByPath() reads CMS collections via loadBlocks() from @decocms/start/cms.
  • Loaders for BlogPostPage, BlogPostItem, BlogpostListing, BlogRelatedPosts, GetCategories, Blogpost, Category, and Author.
  • Unit tests cover post handling (sort/filter/paginate), record retrieval, all loaders, and configure().

• Migration

  • Spread createBlogLoaders() into your COMMERCE_LOADERS map (alias createBlogCommerceLoaders() kept).
  • If you imported ./blog/commerceLoaders, switch to createBlogLoaders from @decocms/apps-start/blog.
  • Use the manifest loader keys in CMS blocks to resolve blog content.

^{Written for commit 55759cf. Summary will update on new commits.}

[github-actions]

🎉 This PR is included in version 4.1.0 🎉

The release is available on:

• v4.1.0
• GitHub release

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