vercel-edge: Missing exports

Present in `@sentry/cloudflare`, absent from `@sentry/vercel-edge`: `vercelAIIntegration`, `updateSpanName`, `setConversationId`, `growthbookIntegration`, `spotlightIntegration`, `prismaIntegration`, `instrumentCreateReactAgent`, `httpServerIntegration`.

`vercelAIIntegration` missing from the Vercel edge runtime is the odd one.

**Work item.** Add the re-exports that apply. For any that genuinely do not work on the edge runtime, leave a comment in `index.ts` saying why.

Compare the exports in @sentry/cloudflare with the Vercel Edge package's index.ts, focusing on the integrations and helpers listed in the issue. Add re-exports that work in the edge runtime, and document any excluded exports in index.ts with the reason. Verify that the package exposes the applicable names without including incompatible ones.

索引モデルが issue の本文から書いたものです。