feat(lnd-ui): on-chain + Lightning balance cards in the summary strip

Fetched from /proxy/lnd/v1/balance/{blockchain,channels}; the cards stay
hidden when the endpoints are unavailable so older deployments are unaffected.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docker/lnd-ui/index.html

@@ -196,6 +196,20 @@
                         <p class="text-sm font-medium text-orange" id="channelCount">0</p>
                     </div>
                 </div>
+                <div class="info-card flex items-center gap-3" id="onchainBalanceCard" style="display:none">
+                    <span style="font-size:1.5rem;color:#f7931a;font-weight:700">&#8383;</span>
+                    <div>
+                        <p class="text-xs text-white-60 mb-1">On-chain</p>
+                        <p class="text-sm font-medium text-white" id="onchainBalance">&mdash;</p>
+                    </div>
+                </div>
+                <div class="info-card flex items-center gap-3" id="channelBalanceCard" style="display:none">
+                    <span style="font-size:1.5rem;color:#4ade80;font-weight:700">&#9737;</span>
+                    <div>
+                        <p class="text-xs text-white-60 mb-1">Lightning Balance</p>
+                        <p class="text-sm font-medium text-white" id="channelBalance">&mdash;</p>
+                    </div>
+                </div>
                 <div class="info-card flex items-center justify-between">
                     <div class="flex items-center gap-3">
                         <div class="status-dot-sm bg-green" id="restDot"></div>
@@ -500,6 +514,12 @@
             if (el) el.textContent = text;
         }
 
+        function formatSats(sats) {
+            if (sats >= 1_000_000) return (sats / 1_000_000).toFixed(2).replace(/\.00$/, '') + 'M sats';
+            if (sats >= 1_000) return (sats / 1_000).toFixed(1).replace(/\.0$/, '') + 'k sats';
+            return sats.toLocaleString() + ' sats';
+        }
+
         async function loadLogs() {
             const logsContent = document.getElementById('logsContent');
             const backendUrl = getBackendUrl();
@@ -532,6 +552,29 @@
                     data.channelCount = (ch.channels && ch.channels.length) || 0;
                 }
             } catch (_) {}
+            // Balances — cards stay hidden when the endpoints are unavailable.
+            try {
+                const wRes = await fetch(backendUrl + '/proxy/lnd/v1/balance/blockchain', { credentials: 'include' });
+                if (wRes.ok) {
+                    const w = await wRes.json();
+                    const sats = Number(w.confirmed_balance ?? w.total_balance ?? 0);
+                    if (!isNaN(sats)) {
+                        setText('onchainBalance', formatSats(sats));
+                        document.getElementById('onchainBalanceCard').style.display = '';
+                    }
+                }
+            } catch (_) {}
+            try {
+                const cRes = await fetch(backendUrl + '/proxy/lnd/v1/balance/channels', { credentials: 'include' });
+                if (cRes.ok) {
+                    const c = await cRes.json();
+                    const sats = Number((c.local_balance && c.local_balance.sat) ?? c.balance ?? 0);
+                    if (!isNaN(sats)) {
+                        setText('channelBalance', formatSats(sats));
+                        document.getElementById('channelBalanceCard').style.display = '';
+                    }
+                }
+            } catch (_) {}
             data.grpcReachable = data.restReachable;
             applyLiveData(data);
         }