[CF1] Microsoft Endpoint Manager - Linux incorrectly shown as supported for device posture check

### Existing documentation URL(s)

- https://developers.cloudflare.com/cloudflare-one/integrations/service-providers/#supported-operating-systems
- https://developers.cloudflare.com/cloudflare-one/integrations/service-providers/microsoft/

### What changes are you suggesting?

The supported OS table incorrectly shows Linux as supported (✅) for
Microsoft Endpoint Manager. This should be ❌.

**Specific change needed:**
- Service providers index page: Change Microsoft Endpoint Manager
Linux column from ✅ to ❌

- Microsoft Endpoint Manager page: Add a note stating Linux is not
supported, e.g.:
"Note: Linux devices are not supported. Microsoft Intune does not
collect hardware details including serial numbers for Linux devices.
Since Cloudflare matches devices using serial numbers, posture checks
will always return empty results for Linux."

**Why:** Microsoft's own documentation states:
"Hardware device details are currently not supported for Linux devices."
(https://learn.microsoft.com/en-us/intune/device-management/inventory-and-status/device-details)

Cloudflare uses serial number as the only identifier to match devices
in Intune. Since Intune doesn't provide serial numbers for Linux,
the check always returns {} and fails.

**How the regression happened:** Commit 980ca318 (Feb 25, 2026)
intentionally added Linux ✅ for SentinelOne (correct), but
accidentally also changed Microsoft Endpoint Manager to ✅ in
the same diff.

### Additional information

_No response_