Primitives Tier 2: box/surface and prose/content across all five themes

[fsecada01]

Split out of #52 so Tier 1 could ship independently (acceptance criterion 7). The primitives layer landed in #53 with the five Tier 1 components — button, badge, heading, label, icon — across all five themes and both template sets. These two containers were scoped out of it deliberately.

What

Component	Measured use in the reference repo	What it is
box / surface	59	A plain bordered/elevated container. Distinct from card, which imposes a header/body/footer structure the caller cannot opt out of. Most uses are just "a thing with a border and some padding."
prose / content	61	Typographic reset for server-rendered or user-supplied HTML — the block where <h2>, <p>, <ul> inside a chunk of markup get sane styling without the caller writing a class per element.

Per component: base wrapper + 5 cotton theme partials + 5 jinja templates = 11 files. 22 for both.

What #53 already settled, and what it does not

Settled, and these should be reused rather than redesigned:

• primitives.py is the vocabulary and the class map, and AXIS_KINDS declares whether an axis's value becomes a class, a tag, or an attribute. A container that takes only class-valued axes needs no new machinery.
• Classes are spelled longhand in the templates because Tailwind's scanner reads source text. A bidirectional parity test binds primitives.py and the templates.
• {% cf_ui_validate %} on the cotton wrapper, validate() in the jinja template.

Not settled, and this is the actual design work:

• prose is the one primitive whose whole job is to wrap markup the caller supplies. Add a primitives layer: button, icon, badge, heading, label across all five themes #52's open question 4 called this out and feat(primitives): a primitives layer — button, badge, heading, label, icon (#52) #53 sidestepped it — Tier 1 primitives take slot content, so docs/escaping.md needed no new rule. prose does not get that luxury: if the content is a SafeString/Markup the caller built, the escaping contract has to be stated explicitly, and if it is user-supplied HTML the docs need to say plainly that cf-ui does not sanitize it and name what should.
• daisy has no prose without the Tailwind typography plugin. prose is a @tailwindcss/typography class, not a daisyUI one. Either the daisy variant declares that plugin as a requirement (and themes.py / the docs say so), or it emits something else. This is the same shape of asymmetry that made grid questionable in Add a primitives layer: button, icon, badge, heading, label across all five themes #52 — decide it explicitly rather than discovering it in a consumer's build.
• Does box take an axis at all? Bulma's box and Bootstrap's border rounded p-3 are not obviously variant-able. An elevation or padding axis may be right, or the component may legitimately have no axes and just be a themed container.

Acceptance criteria

• box/surface and prose/content implemented as base + 5 cotton themes + 5 jinja themes each.
• Names chosen and justified — one name per component, not the slashes above.
• Any new axis added to primitives.py with an AXIS_KINDS entry, a closed vocabulary, and per-theme class maps; the existing parity and drift tests must cover it without modification.
• The daisy prose decision documented in docs/primitives.md — whether it requires @tailwindcss/typography, and if so where that is declared.
• The escaping contract for prose stated explicitly in docs/escaping.md, including that cf-ui does not sanitize caller-supplied HTML.
• Docs page coverage matching the Tier 1 components.