Update dependencies

[thebuilder]

Summary

• update workspace, package, Storybook, docs, test, and build dependencies
• keep the publishable package on TypeScript 6 because tsup@8.5.1 embeds a declaration bundler that crashes with TypeScript 7
• remove the deprecated downlevelIteration option and acknowledge tsup's TypeScript 6 baseUrl deprecation
• enable Biome's full Astro support so frontmatter variables used by templates are not reported as unused

Root cause

The dependency refresh moved the package to TypeScript 7 while leaving tsup at its latest 8.5.1 release. tsup's embedded rollup-plugin-dts@6.1.1 reads compiler internals that are no longer available in TypeScript 7, causing declaration generation to fail with useCaseSensitiveFileNames on undefined.

TypeScript 6 is the newest compatible compiler line for the current tsup build. It also reports the old downlevelIteration setting and tsup's internally supplied baseUrl as deprecated, so the obsolete project option was removed and the remaining tool-owned deprecation was acknowledged in the package tsconfig.

Impact

The updated dependency set now builds successfully on Node 24, produces valid CJS, ESM, and declaration artifacts, and lints Astro templates without false-positive unused-variable warnings.

Verification

• pnpm lint
• pnpm build
• pnpm --filter react-intersection-observer typecheck
• Are The Types Wrong package validation
• Publint
• Size Limit
• git diff --check

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Project	Deployment	Actions	Updated (UTC)
react-intersection-observer	Ready	Preview	Jul 30, 2026 8:30am

[pkg-pr-new]

npm i https://pkg.pr.new/react-intersection-observer@771

commit: f1f85d0