[microfeed] Migrate from d1 alpha to d1 production

Microfeed leverages Cloudflare's D1 database for metadata storage. If you established a Microfeed instance last year or earlier, it is likely utilizing the D1 alpha version. Cloudflare recently announced its plans to phase out the D1 alpha, which will include deleting all databases created with this early version.

To address this change, we have implemented several updates:

1) Enhanced the Microfeed codebase to support seamless migration to the production version of D1.

2) Published a detailed blog post that provides step-by-step guidance on the migration process.

3) Successfully migrated our older Microfeed instances, such as brand-assets.listennotes.com, from D1 alpha to the production environment.

These updates ensure that Microfeed remains robust and reliable.