Pull a reduced end-to-end smoke forward into the slice so the view flow
is exercised over a real on-disk recipe, not just a temp file.
Add fixtures/prose.md — a recipe using only this slice's modelled
constructs (frontmatter, headings, plain paragraphs) so it renders
losslessly. integration_test now runs `kitchen view fixtures/prose.md`
as a subprocess and asserts the frontmatter, separator, headings,
paragraphs, and flat document order end-to-end. smoke_test covers
`kitchen --help` exiting 0 with the view command listed.
The full fixtures/basic.md smoke remains task 0007, which needs 0004's
richer nodes before that fixture renders losslessly.
