[feat](trx-rs): display APRS-IS connection status on About page

Thread aprs_is_status through RigState, RigSnapshot, and the protocol
layer following the same pattern as pskreporter_status. Show the
connection target and callsign when enabled, or "Disabled" otherwise.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-server/src/main.rs

@@ -402,6 +402,25 @@ fn build_rig_task_config(
         Some("Disabled".to_string())
     };
 
+    let aprs_is_status = if rig_cfg.aprsfi.enabled {
+        let cs = rig_cfg
+            .aprsfi
+            .callsign
+            .as_deref()
+            .or(callsign.as_deref())
+            .unwrap_or("");
+        if cs.trim().is_empty() {
+            Some("Enabled but inactive (missing callsign)".to_string())
+        } else {
+            Some(format!(
+                "Enabled ({}:{}, {})",
+                rig_cfg.aprsfi.host, rig_cfg.aprsfi.port, cs
+            ))
+        }
+    } else {
+        Some("Disabled".to_string())
+    };
+
     rig_task::RigTaskConfig {
         registry,
         rig_id: rig_cfg.id.clone(),
@@ -424,6 +443,7 @@ fn build_rig_task_config(
         server_latitude: latitude,
         server_longitude: longitude,
         pskreporter_status,
+        aprs_is_status,
         histories,
         prebuilt_rig: None,
     }
@@ -1007,6 +1027,14 @@ async fn main() -> DynResult<()> {
         } else {
             Some("Disabled".to_string())
         };
+        initial_state.aprs_is_status = if rig_cfg.aprsfi.enabled {
+            Some(format!(
+                "Enabled ({}:{})",
+                rig_cfg.aprsfi.host, rig_cfg.aprsfi.port
+            ))
+        } else {
+            Some("Disabled".to_string())
+        };
         let (state_tx, state_rx) = watch::channel(initial_state);
 
         let mut task_config = build_rig_task_config(

src/trx-server/src/rig_task.rs

@@ -46,6 +46,7 @@ pub struct RigTaskConfig {
     pub server_latitude: Option<f64>,
     pub server_longitude: Option<f64>,
     pub pskreporter_status: Option<String>,
+    pub aprs_is_status: Option<String>,
     /// Per-rig decoder history store.  Used by Reset* commands to clear the
     /// history and by the audio listener to serve history on connection.
     pub histories: Arc<DecoderHistories>,
@@ -78,6 +79,7 @@ impl Default for RigTaskConfig {
             server_latitude: None,
             server_longitude: None,
             pskreporter_status: None,
+            aprs_is_status: None,
             histories: DecoderHistories::new(),
             prebuilt_rig: None,
         }
@@ -136,6 +138,7 @@ pub async fn run_rig_task(
         config.initial_mode.clone(),
     );
     state.pskreporter_status = config.pskreporter_status.clone();
+    state.aprs_is_status = config.aprs_is_status.clone();
 
     // Polling configuration
     let polling = &config.polling;