docs: plan KV-backed fast content deploy

[vibe-dex]

Summary

• Adds FAST_DEPLOY_PLAN.md — an implementation plan to decouple CMS content from worker deploys by moving Studio writes to per-site Cloudflare KV namespaces while keeping the bundled blocks.gen snapshot as a fallback.
• Locks in three architectural decisions: per-block storage granularity, revision-key polling for cross-isolate invalidation (5–10s eventual consistency), and a full async refactor of loadBlock/resolve.ts.
• Splits work explicitly across the @decocms/start framework (new BlockSource abstraction + KV writer + migration scripts), site CI (new sync-content-to-kv.yml, path-filtered deploy.yml), and Studio (POST-to-site publish path with a per-site capability flag).

Test plan

• Plan-only PR — no code yet; reviewers confirm scope, DO/DON'T boundaries, and rollout stages.

🤖 Generated with Claude Code

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Summary by cubic

Adds FAST_DEPLOY_PLAN.md outlining KV-backed fast content deploys: Studio writes go to per-site Cloudflare KV with bundled blocks.gen as a fallback, so content changes no longer trigger worker deploys. The plan defines per-block storage, revision-key polling for cross-isolate invalidation, and an async BlockSource read path across @decocms/start, site CI, and Studio.

• Migration
  • Provision a per-site KV namespace and bind it as DECO_KV.
  • Run migrate-blocks-to-kv once, deploy the updated @decocms/start, and enable the site flag.
  • Add sync-content-to-kv.yml for content-only syncs; run deploy.yml only on code changes.

^{Written for commit 59504c3. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

No issues found across 1 file

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