[HWORKS-2457] Support for versioning in serving deployments

[javierdlrm]

https://hopsworks.atlassian.net/browse/HWORKS-2457

Documents versioning in serving deployments, for model deployments and Python deployments.

• New guide user_guides/mlops/serving/deployment-versions.md: what a version holds and what belongs to the deployment instead, saving a new version, inspecting the versions and rolling back (web UI and Python API), the conflict raised by concurrent changes, and where each version's files are stored.
• serving/index.md and serving/deployment.md link to the guide.
• python-deployment.md gains a short Versions section.
• mkdocs.yml adds the nav entry.
• After review: when a save restarts the deployment and when it does not, an in-place save keeps DEPLOYMENT_VERSION and the deployment_version logging column, scripts from a HopsFS path or git are stored as that path, rollback stays available while a version is updating, the scaling example, screenshots of the three UI actions, and the new serving error codes 240052 to 240055 in the REST error code reference.

Merge order

The guide's API reference links to Deployment.get_versions, Deployment.rollback and DeploymentVersion, which come with logicalclocks/hopsworks-api#1225. Merge after that PR, or the strict build fails on the unresolved references.

Related: logicalclocks/hopsworks-ee#3412, logicalclocks/hopsworks-front#2139, logicalclocks/loadtest#1085, logicalclocks/hopsworks-helm#2435.

Verification

hopsworks-docs check, markdownlint and snakeoil pass locally, with hopsworks-api installed from the HWORKS-2457 branch.

🤖 Generated with Claude Code

[robzor92]

Reads well. I checked it against ee#3412 and api#1225 at their heads:

1. Deprecated API in the examples. Both use predictor.resources.num_instances = 2 (deployment-versions.md:89, python-deployment.md:251), which is deprecated and emits a DeprecationWarning. Use the scaling configuration instead.

2. Restarts (deployment-versions.md:21). "Running instances restart only when the active configuration changes, so a save without changes does not restart the deployment" is true for Save. Two consequences need saying:

   • Save no longer restarts a deployment after you edit a script on the HopsFS mount or add libraries to its environment. Use restart(), or stop and start.
   • Save as new version always creates a version and restarts the deployment, even with no change.

3. Scripts in a version (:28). "A version holds … the predictor and transformer scripts" doesn't hold for Python deployments that read the script from the HopsFS mount or from git. Their version stores the path, not the file, so rolling back doesn't bring the old code back. Worth a note in the Python deployment section too.

4. Version number on in-place saves. An in-place Save keeps the version number, so DEPLOYMENT_VERSION and the feature-logging deployment_version column stay the same across a script change. Logs from before and after the change can't be told apart. Before this change, uploading a new script bumped the number.

5. CI. CI is red only on the three unresolved hsml references. Merge after api#1225, as the description says.

[javierdlrm]

@robzor92 Thanks. Changes:

1. The example uses scaling_configuration.min_instances/max_instances. The Python deployment section no longer has a code block.
2. The intro states that a save without changes neither restarts the deployment nor creates a version, in either mode. It names the two exceptions ee#3412 now implements (a script from a HopsFS path or git, and a changed environment), and says how to restart without saving.
3. Both the guide and the Python deployment section say that a script from a HopsFS path or git is stored as that path, so a rollback restores the configuration but not the code.
4. Added a note that an in-place save keeps DEPLOYMENT_VERSION and the deployment_version logging column, so use "Save as new version" to keep predictions apart.
5. Agreed, merge after api#1225.

Also added the new serving error codes 240052-240055 to the REST error code reference, and that rollback stays available while a version is updating.