[expo 2] Move Runtime to the React 19.2 / React Native 0.86 consumer baseline

[artiphishle]

Closes #25

Summary

• move Runtime to React 19.2.3, React Native 0.86.2, React Native Web 0.21, and TypeScript 6
• keep Runtime Expo-unaware and add dependency/import isolation coverage
• make renderer effects, async loaders, and handler caches compatible with React Compiler assumptions
• add the explicit React Native 0.82-0.86 audit and React Native Web behavioral acceptance coverage
• sync Devtools 1.6 managed tooling for Bun 1.3.14 and Node 24, and add the minor release changeset

Validation

• bun install --frozen-lockfile
• bun test (104 pass, 0 fail)
• bun run typecheck
• TypeScript check under Node 24.19.0
• bun run lint
• bun run format:check
• bun run knip
• bun run build
• bun run docs
• bun run changeset:status
• bunx @ankhorage/ankh doctor validate .
• npm pack --dry-run
• React Compiler healthcheck (11/11 components compiled)

Roadmap: ankhorage/studio#309

[artiphishle]

Reviewed current head 47c80a1 against runtime#25 and Roadmap #309. No merge blockers found.

Key checks:

• React 19.2.3 / RN 0.86.2 / RNW 0.21 / TS 6 baseline matches the roadmap target.
• Runtime remains Expo-unaware in implementation and package dependencies; isolation coverage was strengthened.
• React 19 context/provider changes are valid on the new exact peer baseline.
• Compiler-driven handler-cache and async state/effect rewrites preserve the existing ownership/behavior model; no blanket compiler opt-outs were introduced.
• RN 0.82→0.86 audit covers the required areas and is consistent with the relevant upstream release changes.
• RNW acceptance exercises the real Runtime renderer with react-native resolved to RNW 0.21 and server rendering.
• Direct @ankhorage dependencies are current for this repo; Devtools 1.6 / Bun 1.3.14 / Node 24 managed state is aligned.
• CI is green and the changeset/release boundary is appropriate.

Merge recommendation: ready to merge and release the resulting Runtime minor before [expo 3].