docs: add migration guidance for next release

[ben-reitz]

Summary

• add concise migration guidance to the changesets feeding Version Packages #1995
• map removed Think framework surfaces to their replacements, with Durable Object data-preservation guidance
• document required changes for removed APIs, peer-version floors, and conditional behavior changes
• keep each note scoped to existing users of the affected surface

Updating the source changesets lets the Changesets release PR regenerate the package changelogs after this merges.

Verification

• pnpm run build
• pnpm run check

[changeset-bot]

⚠️ No Changeset found

Latest commit: 4eaeaab

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes changesets to release 7 packages

Name	Type
@cloudflare/think	Minor
@cloudflare/voice	Patch
@cloudflare/worker-bundler	Patch
agents	Minor
@cloudflare/ai-chat	Patch
hono-agents	Patch
@cloudflare/agent-think	Patch

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 1 additional finding.