[codex] Clean up legacy Ghost prompts

[nahiyankhan]

Summary

• remove the private historical packages/ghost-scan package and root map.md
• remove legacy ghost emit --fingerprint direct-markdown support and the legacy-only --no-tokens emit option
• update active docs, generated CLI help, tests, and changeset guidance around canonical .ghost/fingerprint.yml memory

Validation

• pnpm build
• pnpm test -- packages/ghost/test/cli.test.ts
• pnpm check
• pre-push hook: pnpm build, pnpm check, pnpm test

Release note

• changeset: minor

[nahiyankhan]

🤖 Update after follow-up: ghost emit --fingerprint is now removed entirely instead of hard-deprecated with compatibility. The PR also removes the legacy --no-tokens emit option that only applied to the direct-markdown context path. The changeset is now marked major because this removes public CLI flags.

[nahiyankhan]

🤖 Follow-up correction: the changeset is now minor, not major, because Ghost is early enough that this cleanup should land as a minor package-shape/API tightening change.