chore: Rename postgres.new to database.build

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Built bundles:

• Postgres WASM: https://github.com/electric-sql/pglite/actions/runs/11795826381/artifacts/2175656678
• Interim build files: https://github.com/electric-sql/pglite/actions/runs/11795826381/artifacts/2175656812
• PGlite: https://github.com/electric-sql/pglite/actions/runs/11795826381/artifacts/2175678891
• Demos: https://github.com/electric-sql/pglite/actions/runs/11795826381/artifacts/2175697954

[github-actions[bot]]

🚀 Deployed on https://67333681f15450073f6a8741--pglite.netlify.app