docs-preview.yml removed: defer previews to Cloudflare-side setup

Chose to REMOVE the docs-preview.yml workflow and defer previews to Cloudflare-side configuration instead of maintaining CI-driven previews (wrangler versions upload). CI previews looked attractive because they integrate with PRs, but they introduce lifecycle complexity (cleanup, fork guards, artifact handling) and ongoing maintenance burden. By deferring to Cloudflare-native preview mechanisms, the system avoids CI orchestration entirely and keeps the pipeline focused on producing the cloudflare.zip artifact. The release path remains unchanged (CI builds + uploads artifact; Craft deploys). Rejected keeping the workflow because even the Cloudflare-based CI preview still duplicated logic better handled by the platform itself.