feat: implement hostname resolution using gethostname and dns-lookup

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/meta_plugin/hostname.rs

@@ -48,14 +48,28 @@ impl HostnameMetaPlugin {
     }
     
     fn get_hostname(&self) -> String {
-        match hostname::get() {
-            Ok(hostname_os) => {
-                match hostname_os.into_string() {
-                    Ok(hostname) => hostname,
-                    Err(_) => "unknown".to_string(),
+        // First get the short hostname
+        let short_hostname = match gethostname::gethostname().into_string() {
+            Ok(hostname) => hostname,
+            Err(_) => return "unknown".to_string(),
+        };
+        
+        // Try to get the full hostname using DNS lookup
+        // This will work if the hostname can be resolved
+        match dns_lookup::lookup_host(&short_hostname) {
+            Ok(addrs) => {
+                for addr in addrs {
+                    if let std::net::IpAddr::V4(ipv4) = addr {
+                        match dns_lookup::lookup_addr(&ipv4) {
+                            Ok(full_hostname) => return full_hostname,
+                            Err(_) => continue,
+                        }
+                    }
                 }
+                // Fall back to short hostname if resolution fails
+                short_hostname
             }
-            Err(_) => "unknown".to_string(),
+            Err(_) => short_hostname,
         }
     }
 }
@@ -187,3 +201,4 @@ impl MetaPlugin for HostnameMetaPlugin {
         Ok(())
     }
 }
+use gethostname::gethostname;