Prepare 3.0.1 release: bug fixes, deps, and trusted publish workflow

[sebastianwessel]

Summary

• fix fetch response header behavior inside sandbox by reconstructing Headers semantics for guest code
• fix ESM __dirname issue for test-utils mounting and keep CJS compatibility
• harden memfs integration for environments where named runtime exports are brittle
• add timeout cleanup for pending host promises to avoid runtime abort scenarios
• apply docs table fix from pending docs PR
• bump package + JSR versions to 3.0.1 and keep them in sync
• add manual GitHub Actions release workflow with:
  • version sync guard (package.json + jsr.json + workflow input)
  • lint, typecheck, tests, build
  • npm trusted publishing (npm publish --provenance)
  • JSR publishing (npx jsr publish)
• update dependencies to latest (including major upgrades) and refresh lockfile
• fix remaining lint warnings in browser example/theme css

Validation

• bun run lint
• bunx tsc --noEmit
• bun run build
• npm pack --dry-run
• all test files passed when executed individually (bun test <file>)
• repro checks for reported issues __dirname is undefined in ESM build #95, Unable to access headers from the result of a fetch #97, Aborted(Assertion failed) on timeout of an async function #90
• examples verified: example/basic, example/run-tests, example/async

Auto-close Issues

Fixes #97
Fixes #95
Fixes #90
Fixes #93