[feat](trx-frontend-http): add strongest decoded signal summary to map

Add a new "Strongest decoded signal" section below the existing
"Longest decode paths" section on the map tab, showing the top 5
stations with the highest SNR across the current map history window.
Reuses existing map-qso-card styling with SNR displayed in place of
distance.

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

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

@@ -4789,6 +4789,7 @@ function syncDecodeContactPathVisibility() {
     ensureDecodeContactPathRendered(entry);
   }
   renderMapQsoSummary();
+  renderMapSignalSummary();
   updateMapPathsAnimationClass();
 }
 
@@ -6491,6 +6492,115 @@ function renderMapQsoSummary() {
   listEl.replaceChildren(fragment);
 }
 
+function renderMapSignalSummary() {
+  const listEl = document.getElementById("map-signal-summary-list");
+  if (!listEl) return;
+
+  const bestByStation = new Map();
+  for (const entry of locatorMarkers.values()) {
+    if (!entry || (entry.sourceType !== "ft8" && entry.sourceType !== "ft4" && entry.sourceType !== "ft2" && entry.sourceType !== "wspr")) continue;
+    if (!(entry.stationDetails instanceof Map)) continue;
+    for (const detail of entry.stationDetails.values()) {
+      if (!Number.isFinite(detail?.snr_db)) continue;
+      const station = String(detail?.source || detail?.station || "").trim().toUpperCase();
+      if (!station) continue;
+      const snrDb = Number(detail.snr_db);
+      const tsMs = Number.isFinite(detail?.ts_ms) ? Number(detail.ts_ms) : 0;
+      const prev = bestByStation.get(station);
+      if (!prev || snrDb > prev.snrDb || (snrDb === prev.snrDb && tsMs > prev.tsMs)) {
+        bestByStation.set(station, {
+          station,
+          snrDb,
+          tsMs,
+          grid: entry.grid,
+          sourceType: entry.sourceType,
+          bandLabel: bandForHz(Number(detail?.freq_hz))?.label || null,
+        });
+      }
+    }
+  }
+
+  const entries = Array.from(bestByStation.values())
+    .sort((a, b) => {
+      const delta = b.snrDb - a.snrDb;
+      if (Math.abs(delta) > 0.001) return delta;
+      return b.tsMs - a.tsMs;
+    })
+    .slice(0, MAP_QSO_SUMMARY_LIMIT);
+
+  if (entries.length === 0) {
+    const empty = document.createElement("div");
+    empty.className = "map-qso-summary-empty";
+    empty.textContent = "No decoded signals with SNR data in the current map history.";
+    listEl.replaceChildren(empty);
+    return;
+  }
+
+  const fragment = document.createDocumentFragment();
+  entries.forEach((entry, index) => {
+    const card = document.createElement("button");
+    card.type = "button";
+    card.className = "map-qso-card";
+
+    const head = document.createElement("div");
+    head.className = "map-qso-card-head";
+
+    const rank = document.createElement("span");
+    rank.className = "map-qso-card-rank";
+    rank.textContent = `#${index + 1}`;
+    head.appendChild(rank);
+
+    const snr = document.createElement("span");
+    snr.className = "map-qso-card-distance";
+    snr.textContent = `${entry.snrDb >= 0 ? "+" : ""}${entry.snrDb.toFixed(0)} dB`;
+    head.appendChild(snr);
+
+    const body = document.createElement("div");
+    body.className = "map-qso-card-body";
+
+    const pair = document.createElement("div");
+    pair.className = "map-qso-card-pair";
+    pair.textContent = entry.station;
+    body.appendChild(pair);
+
+    const meta = document.createElement("div");
+    meta.className = "map-qso-card-meta";
+
+    const sourceType = document.createElement("span");
+    sourceType.className = "map-qso-card-pill";
+    sourceType.textContent = String(entry.sourceType || "ft8").toUpperCase();
+    meta.appendChild(sourceType);
+
+    if (entry.bandLabel) {
+      const band = document.createElement("span");
+      band.className = "map-qso-card-pill map-qso-card-band";
+      band.style.setProperty("--band-color", locatorBandChipColor(entry.bandLabel));
+      band.textContent = entry.bandLabel;
+      meta.appendChild(band);
+    }
+
+    const ageText = formatTimeAgo(Number(entry.tsMs));
+    if (ageText) {
+      const age = document.createElement("span");
+      age.className = "map-qso-card-pill";
+      age.textContent = ageText;
+      meta.appendChild(age);
+    }
+
+    body.appendChild(meta);
+
+    const grids = document.createElement("div");
+    grids.className = "map-qso-card-grids";
+    grids.textContent = entry.grid || "--";
+    body.appendChild(grids);
+
+    card.appendChild(head);
+    card.appendChild(body);
+    fragment.appendChild(card);
+  });
+  listEl.replaceChildren(fragment);
+}
+
 function buildBookmarkLocatorPopupHtml(grid, bookmarks) {
   const list = Array.isArray(bookmarks) ? bookmarks : [];
   const rows = list

src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html

@@ -782,6 +782,15 @@
         </div>
         <div id="map-qso-summary-list" class="map-qso-summary-list"></div>
       </section>
+      <section class="map-qso-summary" aria-labelledby="map-signal-summary-title">
+        <div class="map-qso-summary-head">
+          <div>
+            <div id="map-signal-summary-title" class="map-qso-summary-title">Strongest decoded signal</div>
+            <div class="map-qso-summary-subtitle">Top 5 strongest signals in the current map history</div>
+          </div>
+        </div>
+        <div id="map-signal-summary-list" class="map-qso-summary-list"></div>
+      </section>
     </div>
     <div id="tab-settings" class="tab-panel" style="display:none;">
       <div class="sub-tab-bar">