Add CachyOS support (#47757)

<!-- Add the related story/sub-task/bug number, like Resolves #123, or
remove if NA -->
**Related issue:** Should Resolve #34591

# Checklist for submitter
- [x] Changes file added 

## User Story
CachyOS lacks from vitals information such as :
* disk encryption status
* disk space
* IP & MAC Addresses
* Installed packages


## Summary
  - Add CachyOS as a recognized Linux platform

## Tests
  - [x] Enroll a CachyOS host and verify it appears as Linux in Fleet
  - [x] Verify disk encryption status displays correctly
- [x] Verify pacman packages are queryable via `fleetd_pacman_packages`
table
  - [x] Disk space, mac address, Public/Private IP are well reported
  - [x] Script are well executed
- [x] No more errors in fleet service logs (level=error
msg="unrecognized platform" hostID=169 platform=cachyos)
  - [ ]  QA'd all new/changed functionality manually


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

## Summary by CodeRabbit

* **New Features**
* CachyOS (Arch-based Linux distribution) is now recognized as a
supported platform, including disk encryption detection and LUKS
support.
* **Bug Fixes**
* Updated host vitals disk-encryption tooltip messaging so CachyOS uses
the correct Linux-specific copy.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: plop28 <plop28@noreply.com>

server/fleet/hosts.go

@@ -985,7 +985,8 @@ func (h *Host) IsDEPAssignedToFleet() bool {
 func (h *Host) IsLUKSSupported() bool {
 	return h.Platform == "ubuntu" ||
 		strings.Contains(h.OSVersion, "Fedora") || // fedora h.Platform reports as "rhel"
-		h.Platform == "arch" || h.Platform == "archarm" || h.Platform == "manjaro" || h.Platform == "manjaro-arm"
+		h.Platform == "arch" || h.Platform == "archarm" || h.Platform == "manjaro" || h.Platform == "manjaro-arm" ||
+		h.Platform == "cachyos"
 }
 
 // IsAppleSilicon returns true if the host is a macOS device with an ARM CPU (Apple Silicon).
@@ -1191,6 +1192,7 @@ var HostLinuxOSs = []string{
 	"archarm",
 	"flatcar",
 	"coreos",
+	"cachyos",
 }
 
 // HostNeitherDebNorRpmPackageOSs are the list of known Linux platforms that support neither DEB nor RPM packages
@@ -1205,6 +1207,7 @@ var HostNeitherDebNorRpmPackageOSs = map[string]struct{}{
 	"manjaro-arm": {},
 	"flatcar":     {},
 	"coreos":      {},
+	"cachyos":     {},
 }
 
 // HostDebPackageOSs are the list of known Linux platforms that support DEB packages