fix: postgres build plugin w --production

[patricebender]

as reported in the issue, with default cds build --production no postgres build artifacts have been generated.

this was due to a misconfiguration in our postgres/package.json

---

cds init reproduce --add tiny-sample
cd reproduce
cds add postgres

you can now observe the malformed cds env

❯ cds env requires.db --profile production
{
  impl: '@cap-js/postgres',
  credentials: { url: 'db.sqlite' },
  kind: 'sqlite',
  dialect: 'postgres',
  vcap: { label: 'postgresql-db' },
  schema_evolution: 'auto'
}

and the broken build (missing postgres build task):

❯ cds build --production
building project [/Users/patricebender/SAPDevelop/dev/cds-dbs/postgres/test/tiny-sample], clean [true]
cds-dk [8.7.1], cds [8.8.0], compiler [5.7.5], home [/Users/patricebender/SAPDevelop/dev/cds]

{
  build: {
    target: 'gen',
    tasks: [
      { for: 'nodejs', src: 'srv', options: { model: ['db', 'srv'] }}
    ]
  }
}

[patricebender]

in this workflow run, the issue has been reproduced: https://github.com/cap-js/cds-dbs/actions/runs/13201485026/job/36854354861?pr=1018#step:7:229