Generate cartoon publish markdown from cuts.json while preserving manual prose

[realproject7]

Parent: #197

Proposal reference: ~/z-docs/PROPOSAL-plotlink-ows-webtoon-pivot.md

Context

plot-NN.cuts.json is canonical. plot-NN.md is publish-facing markdown. OWS should regenerate only marked cut blocks and preserve user-written prose outside those blocks.

Scope

• Generate markdown blocks using markers:

<!-- ows:cartoon-cut cut-001 start -->
![Cut 1](https://ipfs.filebase.io/ipfs/...)
<!-- ows:cartoon-cut cut-001 end -->

• Insert final uploaded image URLs in cut order.
• Preserve text outside generated blocks.
• Warn on stale/missing generated blocks.
• Keep fiction markdown editing unchanged.

Acceptance Criteria

• Generated cut blocks can be regenerated from cuts.json.
• Manual prose outside generated blocks is preserved.
• Missing upload URLs produce readiness warnings instead of broken publish content.
• Tests cover block replacement, prose preservation, reordering, and fiction no-op behavior.

Public Safety

This is a public repo. Do not include secrets, API keys, wallet private keys, mnemonics, auth tokens, OWS vault internals, private story drafts, or sensitive local paths in issues, PRs, logs, docs, tests, or examples.