feat(cms): BlockSource abstraction + bundled fallback [fast-deploy 1/5]

[hugo-ccabral]

Stack 1/5 — Fast Deploy (KV-first content). Base: main.

Decouples CMS content updates from worker code deploys: content served from Cloudflare KV with the bundled blocks.gen snapshot as fallback. Full design + cross-repo contracts in docs/fast-deploy.md (PR 5/5).

This PR

• src/cms/blockSource.ts — BlockSource interface (whole-snapshot model), BundledBlockSource no-op, computeRevision (matches loader.ts DJB2), KV_KEYS contract, and a local minimal KVNamespace type (no @cloudflare/workers-types dep).
• Exports from src/cms/index.ts.

Pure addition — dead code until wired by 2/5. Zero runtime impact.

Test

npx vitest run src/cms/blockSource.test.ts (7 tests). npm run typecheck clean.

Stack

1/5 this · 2/5 read path · 3/5 write-through · 4/5 CI scripts · 5/5 docs

🤖 Generated with Claude Code

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Summary by cubic

Adds a BlockSource abstraction for whole-snapshot CMS content with a no-op BundledBlockSource fallback to enable KV-first fast deploys using blocks.gen as fallback. Introduces computeRevision and a shared KV key contract for consistent revision checks.

• New Features
  • Added src/cms/blockSource.ts: BlockSource, BundledBlockSource, computeRevision, KV_KEYS, and a minimal KVNamespace (no @cloudflare/workers-types).
  • Re-exported from src/cms/index.ts; tests in src/cms/blockSource.test.ts. No runtime change until the read path is wired.

^{Written for commit 8344831. Summary will update on new commits.}