CI: add bundle size and benchmark monitoring

[gr2m]

We received reports of slow import/instantiation times for AI SDK

• Your Worker failed validation because it exceeded startup limits. cloudflare/workers-sdk#10723
• https://dev.to/dzakh/zod-v4-17x-slower-and-why-you-should-care-1m1
• https://x.com/hichaelmart/status/1975328481669226946

We are looking into mitigating the problem.

One thing that we decided is needed is to make bundle size and benchmark monitoring part of our CI

Some relevant insights by @colinhacks

• 4x bundle size increase with CommonJS for v4 and v4-mini vs v3 colinhacks/zod#4637 (comment)
• https://x.com/colinhacks/status/1975609105596490154

Related

• chore(ai): load zod schemas lazily #9275
• typebox exploration #9285

Tasks

• ci(bundle-size): initial version #9411

[vercel-ai-sdk]

👋 Thanks for opening this issue! I was unable to automatically detect which AI provider this issue relates to. A maintainer will review and apply the appropriate provider/* labels manually.