Unify CSS-to-RN compiler and runtime pipeline

[cray0000]

Summary

This PR unifies the CSS-to-React-Native style pipeline into a new @cssxjs/css-to-rn workspace package and wires CSSX, loaders, Babel output, and runtime entrypoints through it. The goal is to replace the separate forked CSS-to-RN transform libraries and the old CSSX runtime with one maintainable compiler/runtime package.

Key changes:

• Adds packages/css-to-rn, a TypeScript ESM package owning CSS parsing, selector IR, value resolution, property transforms, style resolution, caching, and React runtime tracking.
• Keeps Stylus-to-CSS compilation separate, while moving pure CSS-to-RN style compilation and runtime resolution into the unified package.
• Supports local JS template interpolation in function-scoped css/styl templates, with interpolation values reusing one cache slot per compiled call shape.
• Adds runtime CSS string compilation for generated CSS via useRuntimeCss(), useCssxLayer(), and cssx().
• Implements nested var() resolution, partial shorthand substitution, dynamic dependency tracking, bounded cache behavior, deep inline-style hashing, media/dimension tracking, web matchMedia invalidation, and React Native Dimensions integration.
• Adds React 19 tracking without Teamplay or @nx-js/observer-util, including Suspense/aborted-render cleanup tests.
• Adds CssxProvider style and theme for subtree-scoped provider CSS, global utility classes, scoped :root / :root.<theme> variables, OS dark-mode auto selection, and component tag overrides.
• Adds CSSX theme assets and exports: cssxjs/themes/tailwind and cssxjs/themes/shadcn.
• Adds @custom-media, CSS media range evaluation for width/height comparisons, built-in @media (--theme-*) aliases, and provider-aware useMedia().
• Adds component tag selectors through themed(tagName, Component), including Tag, Tag.class, Tag:part(name), Tag::part(name), Tag:hover, and Tag:active matching.
• Adds useCssVariable(), useCssVariableRaw(), getCssVariable(), and getCssVariableRaw() for subscribed and global JS access to resolved CSS variables.
• Adds useCssColor() and getCssColor() for provider-aware JS color bridges, including token lookup and color-mix() style mixing.
• Adds a deprecated JS u() helper and build diagnostics for deprecated CSS u units.
• Adds validating variables and defaultVariables proxy methods: .assign(), .set(), and .clear().
• Resolves var() inside inline style props and tracks the variables used by those inline props.
• Normalizes oklch(), oklab(), and color-mix() through pinned @colordx/core@5.4.3 so modern color CSS works on RN.
• Supports percentage/unitless calc() in CSS value resolution for color-channel math while still rejecting mixed layout calc such as calc(100% - 16px).
• Mixes color-mix(in srgb, color, transparent) with premultiplied alpha so transparent theme colors preserve the source RGB.
• Preserves source-condition TypeScript consumers without committing build output: source entrypoints carry vendor shims, themed() preserves wrapped component props, and cssx() accepts loader-produced opaque sheet records at the type boundary.
• Implements :hover/:active aliases, filter, background-image/gradient support, limited background shorthand, animations/transitions/keyframes, and Reanimated v4-compatible animation style output.
• Adds build-strict diagnostics for unsupported static declarations while keeping runtime compilation graceful for generated CSS.
• Migrates loaders and Babel runtime paths to the unified package, with source-condition test/dev imports and facade smoke coverage.
• Stops tracking generated dist output; package builds still emit dist for published/default exports.
• Keeps legacy runtime/*-teamplay import paths as compatibility wrappers only.
• Removes the old packages/runtime package from the active graph.
• Updates architecture.md, AGENTS.md, plan.md, public docs, README credits, and CI smoke checks for the new architecture.

Architect Review Follow-up

After a multi-agent architecture/performance/test-coverage review, this PR now also:

• avoids promoting changed tracked sheets, interpolation values, or hook dependencies from Suspense-aborted renders
• keeps useCssxLayer(false) hook order stable when toggled to a real sheet
• allows and resolves template interpolation inside provider :root custom property values
• resolves provider root variables from compiled sheets and { sheet, values } layers
• adds regression coverage for complex partial var() values in box-shadow/filter/text-shadow/transform/background
• updates runtime docs for precompiled provider :root interpolation

Related PRs

• Wire StartupjsProvider to CSSX startupjs#1327 wires StartupjsProvider style and theme into CSSX so framework users can pass provider CSS and theme selection through the StartupJS root provider.
• Move StartupJS UI theme system to CSSX startupjs-ui#41 moves StartupJS UI theming onto CSSX theme assets, startupjsUiTheme.cssx.css, CSS variable primitives, and direct component tag/part overrides.

Validation

• cd packages/css-to-rn && npm test
• yarn test
• yarn docs-build
• git diff --check
• Cross-repo validation with local source links for StartupJS and StartupJS UI provider/theme integration.
• startupjs-ui PR validation: node scripts/check-startupjs-ui-exports.mjs, yarn install --immutable --mode=skip-build, targeted eslint, and direct CSS-template compile smoke over packages/ plus startupjsUiTheme.cssx.css.
• startupjs PR validation: NODE_OPTIONS="-C cssx-ts" npm test in core/startupjs, plus the normal pre-commit hook with eslint and npx startupjs check.

Review Focus

This is a large architectural PR. Please scrutinize:

• Runtime cache invalidation, interpolation cache behavior, and reference stability.
• Provider :root / :root.<theme> variable scoping and precedence relative to runtime/default variables.
• Theme selection, OS color-scheme subscriptions, and @media (--theme-*) behavior.
• @custom-media, range media evaluation, and useMedia() subscriptions.
• Component tag selector matching and the themed() render-local tracking model.
• useCssVariable() / useCssColor() exact subscriptions and Suspense/aborted-render safety.
• Media/dimension invalidation, web matchMedia subscriptions, React Native dimensions, and listener cleanup.
• Complex value parsing: nested var(), shorthand fragments, modern colors, gradients/backgrounds, transforms, animations, transitions, and invalid generated CSS.
• Babel output compatibility with existing CSSX styleName, css, styl, and part workflows.
• Package exports/source-condition behavior and whether the new package boundary is maintainable long term.