[codex] Add story settings and Moment links

[jhull]

Summary

• Adds optional story.settings[] as a reusable story-level Setting glossary.
• Adds optional moment.setting_id so Moments can reference a shared Setting while keeping their required free-text setting field.
• Updates schema docs, the main specification, and examples to show repeated Moment settings without duplicating place details.

Rationale

This accepts the useful part of the locations proposal while aligning it with existing NCP terminology. The concept maps to moment.setting, so the canonical field is settings, not locations. The shared glossary is story-level, while setting_id on Moments provides the explicit linkage when producers need it.

The change is additive: producers can keep emitting only free-text moment.setting; consumers that do not understand settings or setting_id can ignore them.

Validation

• npm run validate:file -- examples/story-settings.json passed.
• JSON/YAML schema twins compare equal via Ruby JSON.parse + YAML.load_file.
• git diff --check passed.

Known existing suite state: npm run validate:schema still fails on pre-existing valid fixture/schema mismatches around Storybeat additional properties and two storypoint-throughline fixtures missing narrative titles. The new examples/story-settings.json fixture passes in that run.