feat: composite section blocks (section.*)

[odenirdev]

Composite section blocks (section.*)

Ships an engine-owned palette of composite sections — section.hero and
section.cta — that are admitted into the page body Dynamic Zone automatically,
render as semantic HTML branded by the adopter's theme, and are overridable via
BlockRenderer. It mirrors the existing press.* reference-block mechanism into a
separatesection.* category, preserving the three-palette split
(press.* atoms / section.* sections / custom.* adopter).

What's in it

Layer	Change
CMS (press-cms)	Injects section.hero/section.cta under a new section category (deterministic globalId); admits them statically into the page DZ (page/schema.json). serialize-schema unchanged.
Type-sync	Generator emits SectionHero/SectionCta + the PageBody union with zero generator change — v1 fields are all flat scalar/media/enum (pinned by a test).
Web (press-web)	Tolerant Hero/Cta renderers (no title → nothing; CTA/button only when both parts present — no dead links). Separate sectionBlocks registry; BlockRenderer merges { ...referenceBlocks, ...sectionBlocks, ...components } so adopters still win last and can override any section.
Theme	theme.css section rules are a pure var(--press-*) token consumer — sections are born branded by Site Settings, no override required.
Release	CLAUDE.md documents the third palette; changeset bumps both engine packages minor.

Invariants held

• Additive & non-breaking: press.* and custom.* untouched; press.hero stays removed.
• PressSchema type-only on both sides; generator references no Strapi/React types.
• Adopters get section.* for free on press upgrade — no host-template change.

Verification

• pnpm -r test → cli 21/21, cms 24/24, web 146/146; pnpm -r typecheck clean; pnpm build (incl. cms strapi-plugin build + playground Next build) green.
• Whole-branch review verdict: Ready to merge (zero Critical/Important). Type coherence verified across all five layers; registry-key identity byte-identical; generator/serializer change count zero.

⚠️ Before merge/release — live dogfood (Task 9, manual)

Not yet done (needs the running app): boot pnpm play, author a Hero + CTA page in the admin, confirm both render branded on :3000, and commit the regenerated apps/playground/.../generated.ts if the sync changes it. Also eyeball the hero image+content layout (single-column display:grid — add grid-template-columns if side-by-side is wanted).

🤖 Generated with Claude Code