[feat](trx-client): add configurable initial map zoom

Add an HTTP frontend config option for the initial APRS map zoom,
expose it through frontend metadata, and apply it in the web UI.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js

@@ -1247,6 +1247,7 @@ let serverCallsign = null;
 let ownerCallsign = null;
 let serverLat = null;
 let serverLon = null;
+let initialMapZoom = 10;
 
 function updateFooterBuildInfo() {
   const serverEl = document.getElementById("footer-server-build");
@@ -1274,6 +1275,9 @@ function render(update) {
   }
   if (update.server_latitude != null) serverLat = update.server_latitude;
   if (update.server_longitude != null) serverLon = update.server_longitude;
+  if (typeof update.initial_map_zoom === "number" && Number.isFinite(update.initial_map_zoom)) {
+    initialMapZoom = Math.max(1, Math.round(update.initial_map_zoom));
+  }
   updateTitle();
   updateFooterBuildInfo();
 
@@ -2406,7 +2410,7 @@ function initAprsMap() {
 
   const hasLocation = serverLat != null && serverLon != null;
   const center = hasLocation ? [serverLat, serverLon] : [20, 0];
-  const zoom = hasLocation ? 10 : 2;
+  const zoom = hasLocation ? initialMapZoom : 2;
 
   aprsMap = L.map("aprs-map").setView(center, zoom);
   updateMapBaseLayerForTheme(currentTheme());

src/trx-client/trx-frontend/trx-frontend-http/src/api.rs

@@ -37,6 +37,7 @@ struct FrontendMeta {
     rig_ids: Vec<String>,
     owner_callsign: Option<String>,
     show_sdr_gain_control: bool,
+    initial_map_zoom: u8,
 }
 
 #[get("/status")]
@@ -85,6 +86,10 @@ fn inject_frontend_meta(json: &str, meta: FrontendMeta) -> String {
         "show_sdr_gain_control".to_string(),
         serde_json::json!(meta.show_sdr_gain_control),
     );
+    map.insert(
+        "initial_map_zoom".to_string(),
+        serde_json::json!(meta.initial_map_zoom),
+    );
 
     serde_json::to_string(&value).unwrap_or_else(|_| json.to_string())
 }
@@ -101,6 +106,7 @@ fn frontend_meta_from_context(
         rig_ids: rig_ids_from_context(context),
         owner_callsign: owner_callsign_from_context(context),
         show_sdr_gain_control: show_sdr_gain_control_from_context(context),
+        initial_map_zoom: initial_map_zoom_from_context(context),
     }
 }
 
@@ -138,6 +144,10 @@ fn show_sdr_gain_control_from_context(context: &FrontendRuntimeContext) -> bool
     context.http_show_sdr_gain_control
 }
 
+fn initial_map_zoom_from_context(context: &FrontendRuntimeContext) -> u8 {
+    context.http_initial_map_zoom
+}
+
 #[get("/events")]
 pub async fn events(
     state: web::Data<watch::Receiver<RigState>>,