chore(release): prepare solid-email 0.1.5

[Akin01]

Summary

• Bumped @akin01/solid-email and @solid-email/render to 0.1.5, including monorepo metadata, the Solid Email skill metadata, and e2e fixture tarball references.
• Updated CHANGELOG.md for the 0.1.5 release notes, including PR feat(benchmarks): add cross-library email benchmark suite #14 related commits.
• Added cross-library benchmark results to README.md and bolded the best benchmark numbers.
• Included the packages/solid-email/src/render-shim.d.ts declaration shim in the cross-library benchmark tsconfig so its package-local typecheck covers source imports cleanly.

Verification

• pnpm exec biome check package.json packages/solid-email/package.json packages/render/package.json skills/solid-email/SKILL.md README.md CHANGELOG.md benchmarks/cross-library/tsconfig.json e2e/vite/package.json e2e/tanstack-start/package.json e2e/cloudflare-tanstack-start/package.json e2e/vite/pnpm-workspace.yaml e2e/tanstack-start/pnpm-workspace.yaml e2e/cloudflare-tanstack-start/pnpm-workspace.yaml
• pnpm test
• pnpm test:e2e
• pnpm --filter @benchmarks/cross-library run typecheck
• pnpm benchmark:cross-library
• node scripts/create-github-releases.mjs --dry-run --package-version @solid-email/render@0.1.5 --package-version @akin01/solid-email@0.1.5

Checklist

• Tests or examples cover the changed behavior.
• Types were checked without suppressions.
• Public API changes are reflected in docs or examples. Not applicable: no public API changes.