Add Cloudflare as a host platform

[chenzhiwei]

Cloudflare has Workers for compute, D1 for database, R2 for object storage, could you please support deploying Hollo to Cloudflare?

[dahlia]

Cloudflare Workers deployment may be feasible if Hollo keeps PostgreSQL, likely via Hyperdrive, and replaces platform-specific pieces such as Fedify queue/KV, storage, background jobs, and media processing.

Full D1 support is a much larger database-portability project because Hollo's schema and queries are PostgreSQL-specific, while Drizzle schemas are dialect-specific. This should not be treated as a small hosting-platform task.