fix: add missing plugins to release-it bumper

[steve-calvert-glean]

Summary

• glean-dev-docs, glean-skills, glean-productivity, and glean-project were missing from the @release-it/bumper out array
• Without this fix, their versions would silently drift behind the marketplace version on every release
• Bumper now covers all 10 plugins (12 entries total including package.json and marketplace.json)

Test Plan

• Verify bumper has 12 entries: node -e "const c=JSON.parse(require('fs').readFileSync('.release-it.json','utf8')); console.log(c.plugins['@release-it/bumper'].out.length)"