Api endpoint to get deployment manifest with expanded runtime config

Is your feature request related to a problem? Please describe.

As a bosh operator, in order to record a reliable current state of a bosh deployment, I need a deployment manifest with the applied runtime config. Then I archive this deployment manifest (typically in git) in order to track history of changes applied by my automation pipelines.

Currently, the runtime config may change, but the current endpoint has not yet options to render the applied runtime config. For cloud-config, it does support indicating the cloud-config within the deployment is outdated, see https://github.com/cloudfoundry/bosh/blob/69dea967cf0a45f1468d749b651fa1b84d894a73/src/bosh-director/spec/unit/api/controllers/deployments_controller_spec.rb#L1073-L1100

Describe the solution you'd like

A new param to the /deployments/<deployment> endpoint to render the deployment manifest along with the add-ons.

Describe alternatives you've considered

I looked for existing task debug traces and could not find a dumped rendered manifest.

Looking at source code, the planner below seems to perform the manifest merge but does not yet dump it https://github.com/cloudfoundry/bosh/blob/4f0656826132d4794d4e5070381717ba067f9cc4/src/bosh-director/lib/bosh/director/deployment_plan/planner_factory.rb#L50-L126
A clear and concise description of what you want to happen.

I'm also considering fetching the full manifest directly from the director db, but would need guidance into the current director db schema, as https://github.com/cloudfoundry/bosh/tree/main/docs/director_schema seems outdated

Start with the deployments controller spec around the cloud-config behavior at the linked lines, then trace the /deployments/ endpoint and planner_factory.rb where the manifest merge occurs. Done means the endpoint can request and return a deployment manifest with the applied runtime config and add-ons, with coverage for the new behavior.