<!-- Add the related story/sub-task/bug number, like Resolves#123, or
remove if NA -->
**Related issue:** Resolves#49511 and #46837 as a whole
# Checklist for submitter
If some of the following don't apply, delete the relevant line.
- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.
- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements), JS
inline code is prevented especially for url redirects, and untrusted
data interpolated into shell scripts/commands is validated against shell
metacharacters.
- [x] Timeouts are implemented and retries are limited to avoid infinite
loops
- [x] If paths of existing endpoints are modified without backwards
compatibility, checked the frontend/CLI for any necessary changes
## Testing
- [x] Added/updated automated tests
- [x] Where appropriate, [automated tests simulate multiple hosts and
test for host
isolation](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/reference/patterns-backend.md#unit-testing)
(updates to one hosts's records do not affect another)
- [x] QA'd all new/changed functionality manually
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added support for Fleet built-in variables in host scripts, software
installer scripts, setup-experience scripts, and maintained-app
installer scripts.
* Variables are resolved per host at execution time; saved content
remains unexpanded.
* **Bug Fixes**
* Requests now validate Fleet variables up-front, with clear
script-specific error messages for unsupported variables.
* Added improved messaging when variable resolution fails during
execution.
* Enforced Fleet Premium licensing for script/installer flows that use
Fleet variables.
* **Documentation**
* Documented supported variables and Premium requirements, including
usage examples.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Jordan Montgomery
89f67544b4