Add host name template types, activity, and validation

[juan-fdz-hawa]

Related issue: Relates to #48621

• Add name_template to TeamMDM, TeamSpecMDM and TeamPayloadMDM.
• Add the edited_host_name_template activity type.
• Add ValidateHostNameTemplate and ResolveHostNameTemplate in server/fleet/name_template.go.

Checklist for submitter

If some of the following don't apply, delete the relevant line.

Testing

• Added/updated automated tests

Summary by CodeRabbit

• New Features

  • Added support for setting a host display name template for fleet-managed devices.
  • Host name templates now accept approved variables and can be previewed from host data.

• Bug Fixes

  • Improved validation to reject invalid, empty, overlong, or unsafe templates.
  • Clearing a template is now handled cleanly and shown correctly in activity history.

[juan-fdz-hawa]

@coderabbitai full review

[coderabbitai]

✅ Action performed

Full review finished.

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 4722bd20-9997-4a9d-ae0c-3e429543deeb

📥 Commits

Reviewing files that changed from the base of the PR and between 5fc14b8 and f8213c0.

📒 Files selected for processing (6)

• server/fleet/activities.go
• server/fleet/name_template.go
• server/fleet/name_template_test.go
• server/fleet/teams.go
• server/fleet/teams_test.go
• tools/dibble/pkg/seed/activities.go

---

Walkthrough

This PR adds host name template functionality to Fleet. It introduces ValidateHostNameTemplate and ResolveHostNameTemplate functions supporting a restricted set of $FLEET_VAR_HOST_* variables, a new ActivityTypeEditedHostNameTemplate activity type, and NameTemplate fields on TeamPayloadMDM, TeamMDM, and TeamSpecMDM structs using optjson.String where distinguishing "clear" from "unset" matters. Unit tests cover validation, resolution, JSON round-tripping, and activity marshaling. The dibble seed tool is updated to include the new activity template.

Sequence Diagram(s)

Not applicable — this PR primarily adds data validation/resolution logic and type definitions rather than a new interactive request/response flow.

Possibly related issues

• Rename hosts: config types, template validation, and activity type #48621: Implements the same host rename/template work described, including name_template team config fields, validation/resolution helpers, and the edited_host_name_template activity type.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description includes the issue and testing, but omits most template checklist items and doesn't mark non-applicable sections.	Fill in or remove each template section as applicable, especially changes files, validation, testing details, migrations, and GitOps/config-setting checks.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main change set.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 48621-rename-hosts-config-types-template-validation-and-activity-type

---

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

@@                          Coverage Diff                          @@
##             38806-macos-iosipados-rename-hosts   #48699   +/-   ##
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Flag	Coverage Δ
backend	69.64% <100.00%> (?)

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[lucasmrod]

LGTM! Left two comments/questions.