[#174] Add NSFW flag and language to publish flow

[realproject7]

Summary

• Add language selector dropdown to PreviewPanel genesis publish UI (auto-detects from structure.md)
• Add NSFW checkbox with info note to PreviewPanel genesis publish UI
• Pass language and isNsfw through the full publish chain: PreviewPanel → StoriesPage → route → publish lib → IPFS metadata + PlotLink indexer
• Backwards compatible: defaults to English / not NSFW when fields are missing
• Update AGENTS.md with NSFW content guidance and language auto-detection docs

Test plan

• Verify language dropdown appears for genesis files in PreviewPanel
• Verify NSFW checkbox appears for genesis files with info note when checked
• Verify language auto-detects from **language**: Korean in structure.md
• Verify publish sends language and isNsfw to indexer (check network tab)
• Verify plot publish still works (language forwarded, no isNsfw)
• Verify backwards compat: existing stories without these fields publish normally

Fixes #174

🤖 Generated with Claude Code

[project7-interns]

Verdict: REQUEST CHANGES

Summary

The UI additions and field plumbing are mostly in place, but the backend path does not implement the required backwards-compatible defaults. Existing callers that omit the new fields will still send undefined to IPFS/indexing instead of English / false.

Findings

• [high] Missing backwards-compatible defaults for language and NSFW
  • File: app/lib/publish.ts:339
  • Suggestion: Normalize at the publish boundary, e.g. const normalizedLanguage = language || "English" and const normalizedIsNsfw = isNsfw ?? false, then pass those normalized values to both IPFS metadata and the PlotLink indexer (isNsfw: String(normalizedIsNsfw)). As written, route/API callers that omit the new optional fields produce { language: undefined, isNsfw: undefined }, which fails the issue acceptance criterion that missing fields default to English / not NSFW.

Decision

Requesting changes because one explicit acceptance criterion is not met. CI was still pending at review time.

[project7-interns]

Verdict: APPROVE

Summary

The requested defaults are now normalized at the publish boundary, and isNsfw is passed to the indexer as a boolean. The publish UI, route forwarding, IPFS metadata language field, and AGENTS.md guidance match the issue scope.

Findings

• None.

Decision

Approving. Note: gh pr checks currently reports no checks on the latest branch head, so I could not confirm CI from the review CLI output.