Postkit 0.3.0. Bring your own design system.

This release separates what a component is from how it looks. Definitions live in @postkit/core, @postkit/react renders them as headless views, and today's Chakra components move to @postkit/chakra. Your posts don't change.

Added

• createPostkit and kits: enable only the components you use, and ship only those.
• Defaults, slot parts and views: change what authors get with defaults in createPostkit, swap one part, or replace the render, all without ejecting.
• postkit eject and postkit diff, from the new @postkit/cli: own a component's source and still see what changed upstream.
• Footnotes and sidenotes, carried through every renderer including email.
• An optional styles.css baseline for the headless views, driven by --postkit-* tokens.
• renderEmail() in @postkit/email, which turns a Markdown, MDX or @postkit/core document into email HTML and plain text.
• Device, a screenshot in a plain iPhone, iPad or Mac frame drawn with CSS (kind, src, alt, caption). It's experimental.
• Carousel presentation="peek": the current item centred with its neighbours faded either side, arrows only, and its caption announced to screen readers. Like every carousel, it never advances on its own.
• Gallery presentation="row": two or three related pictures side by side, which become a swipeable rail on phones.
• Video captions (a WebVTT track), captionsLang, duration and decorative.
• Figure numbering: <PostkitProvider figures="numbered"> labels figures, videos and devices "Fig. 1", "Fig. 2"…, and the items of a carousel or gallery "Fig. 3", "Fig. 3b", "Fig. 3c".

Changed

• @postkit/react renders headless views for every static component. Interactive components whose behaviour isn't shared yet stay Chakra-only until 0.3.x, and the component manifest marks them.
• Chakra recipes follow the host's colour mode, with dark values for every colour in postkitDefaultTheme.
• Every component now defaults to the subtle variant (D12). Pass variant="outline", or set defaults in createPostkit, to keep the 0.2 look.
• Email support is computed from what the email renderer exports, and every component declares an email fallback.
• Callout accepts type as an alias for tone, in directives and in MDX. tone stays the documented prop, and wins if both are set.
• A Video without a captions track now gets a warning, in development and in your build output, unless you mark it decorative. It never fails the build, even in strict mode, so this isn't a breaking change.
• Poll, Chart and SocialPost are marked experimental in the component manifest until they've been reviewed.

Removed

• The unused async, colors, strings and utils packages.

Migrating from 0.2

If you render with Chakra, change one import. Component names and props are unchanged.

// 0.2
import { Callout, PostkitProvider } from '@postkit/react';

// 0.3
import { Callout, PostkitProvider } from '@postkit/chakra';

Want only the components you use? Move to createPostkit when you're ready. The old exports keep working through 0.x.