ci: support npm authenticated publishing

[nahiyankhan]

🤖 This PR updates the Release workflow so @anarchitecture/ghost can publish through either repo-provided npm credentials or npm Trusted Publishing.

Changes:

• Updates actions/setup-node to v6 and uses Node 24 for a modern npm CLI.
• Publishes the package with npm publish ./packages/ghost --access public --provenance so npm OIDC/trusted publishing can work.
• Reads the npm token from either NPM_PUBLISH_TOKEN or the conventional NPM_TOKEN GitHub Actions secret.
• Removes the separate NODE_AUTH_TOKEN env because Changesets writes npm auth from NPM_TOKEN when a token is present.

Local verification:

• pnpm check
• pnpm build
• pnpm test via pre-push, 479 tests passing
• npm_config_cache=/private/tmp/ghost-npm-cache npm pack ./packages/ghost --dry-run --ignore-scripts

Remaining setup before merging the release PR:

• Add a repo secret named NPM_PUBLISH_TOKEN or NPM_TOKEN containing an npm publish token for @anarchitecture/ghost; or
• Configure npm Trusted Publishing for package @anarchitecture/ghost with owner block, repository ghost, workflow Release, and branch main.