fix: FQDN resolution and display_name blank bug; fix: Arch/Alpine/RPM packages

Bug fixes:
- get_fqdn() now prioritizes 'hostname -f' (returns full FQDN) over /etc/hostname (returns short hostname)
- Added get_hostname() for short hostname extraction
- Added hostname field to EnrollmentRequest for manager display_name population
- Updated SPEC.md and API_DOCUMENTATION.md

Package fixes:
- Arch: Added linux-patch-api.install with post_install/upgrade/remove hooks, user creation, directory creation, config handling
- Alpine: Added linux-patch-api.apk-install with pre/post install/deinstall hooks, user creation, directory creation, config handling, missing config.yaml.example
- RPM: Dynamic version from Cargo.toml, %ghost %config(noreplace) for live configs, tarball exclusions, /var/log in %files

src/enroll/mod.rs

@@ -16,8 +16,8 @@ pub use client::{
 };
 /// Re-export identity extraction functions.
 pub use identity::{
-    get_fqdn, get_ip_addresses, get_ip_for_interface, get_machine_id, get_os_details,
-    get_primary_ip, get_route_source_ip, is_container_bridge, is_link_local,
+    get_fqdn, get_hostname, get_ip_addresses, get_ip_for_interface, get_machine_id,
+    get_os_details, get_primary_ip, get_route_source_ip, is_container_bridge, is_link_local,
 };
 
 /// Run the full enrollment flow against the manager at the given URL.