Add experimental.runtimeServerDeploymentId (#86865)
If this is set, `process.env.NEXT_DEPLOYMENT_ID` is available at runtime, and we don't need to inline the build-time value into the build output.
This is currently true for Node.js routes, and will also be the case for edge routes once https://github.com/vercel/next.js/pull/86769 is merged.
`experimental.runtimeServerDeploymentId` defaults to true when deploying on Vercel and `NEXT_DEPLOYMENT_ID` is set.
- [x] Perform `config.deploymentId = process.env.NEXT_DEPLOYMENT_ID` in the right places in the server
This brings us to this state regarding the deployoment ids in the output (notice the exclusion field):
<img width="628" height="323" alt="Bildschirmfoto 2025-12-05 um 21 17 53" src="https://github.com/user-attachments/assets/6e35997f-3f81-4da4-880e-d1d1984f7272" />
