feat(wallet): a balance that isn't loaded yet says so, in pixels

An unloaded balance rendered as `0`. Zero is not a loading state — it is
a number, and it is the one number that frightens people. Someone
opening the dashboard while the RPCs were still in flight was told, in
the wallet's own typeface, that their money was gone.

There is no formatting fix for that. The fix is to stop claiming a
figure we do not have, so `null` now means "not known yet" and `0` means
"none", and the two are kept apart end to end: the refs start at null,
a rail becomes a number only when its call actually succeeds, and a
snapshot key that was never written stays unknown instead of becoming a
zero.

In place of the figure, a small dot-matrix scans in the rail's own
colour. It inherits currentColor, so on-chain shimmers orange, Lightning
yellow, Cashu purple, Fedimint blue and Ark teal with no colour table to
keep in sync — and it is sized to the figure it stands in for, so
nothing jumps when the real number lands. It carries role="status" and
names what it is waiting for; a shimmering box with no text is nothing
at all to a screen reader.

Two consequences worth stating. The total is withheld until every rail
that makes it up is known — summing nulls as zero would show a total
*lower* than the rails beneath it, which is worse than showing nothing
because it looks authoritative. And the Ark row stays hidden while its
balance is unknown, since "unknown" must not be read as "> 0" on the
many nodes with no Ark sidecar.

The LND app UI had the same bug in a different shape: its tiles start as
an em-dash, but renderBalances() runs on every poll including before the
first response, and `num(null && …)` is 0 — so the dashes were painted
over with "0 sats" almost immediately. Same treatment, in plain CSS.

Also fixes a stale assertion in AppHeroSection's suite, which has been
red since 9ccc325a changed "Restarting..." to a real ellipsis; and two
test proofs that used a plausible-looking hex string for `C`. The V3
codec never parses that field so it went unnoticed, but the V4 encoder
hands it to the reference implementation, which checks the point is
actually on secp256k1. Real curve points now.

Frontend: 996 tests green. Backend: 1436 green.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docker/lnd-ui/index.html

@@ -190,6 +190,16 @@
         .text-white-40 { color: rgba(255,255,255,0.4); }
         .text-green { color: #4ade80; } .text-orange { color: #fb923c; } .text-red { color: #f87171; }
         .text-purple { color: #a78bfa; } .text-yellow { color: #facc15; } .text-btc { color: #f7931a; }
+
+        /* Pixel readout shown in place of a balance that isn't known yet.
+           An unloaded balance used to render as "0 sats" — zero is a number,
+           not a loading state, and it is the one number that frightens
+           people. It inherits currentColor, so each tile shimmers in its own
+           rail colour. */
+        .bal-pixels { display: inline-grid; grid-template-columns: repeat(14, 4px); grid-auto-rows: 4px; gap: 1px; vertical-align: 0.15em; }
+        .bal-pixels i { width: 4px; height: 4px; border-radius: 0.5px; background: currentColor; opacity: 0.16; animation: bal-pixel-scan 1.4s ease-in-out infinite; }
+        @keyframes bal-pixel-scan { 0%, 70%, 100% { opacity: 0.16; } 25% { opacity: 1; } 45% { opacity: 0.42; } }
+        @media (prefers-reduced-motion: reduce) { .bal-pixels i { animation: none; opacity: 0.35; } }
         .bg-green { background: #4ade80; } .bg-yellow { background: #facc15; } .bg-red { background: #f87171; }
         .bg-grey { background: rgba(255,255,255,0.35); }
 
@@ -1070,6 +1080,23 @@
         }
 
         function setText(id, text) { const el = document.getElementById(id); if (el) el.textContent = text; }
+
+        // 28 cells = 14 columns x 2 rows, delays staggered so the lit column
+        // travels across the matrix.
+        const BAL_PIXELS = '<span class="bal-pixels" role="status" aria-label="Loading balance">' +
+            Array.from({ length: 28 }, function (_, i) {
+                return '<i style="animation-delay:' + (i * 45) + 'ms"></i>';
+            }).join('') + '</span>';
+
+        // Render a balance, or the pixel readout when it is not known yet.
+        // `sats` must be null/undefined for "not loaded" — passing 0 here
+        // means the node genuinely has nothing, and says so.
+        function setBalance(id, sats) {
+            const el = document.getElementById(id);
+            if (!el) return;
+            if (sats === null || sats === undefined) { el.innerHTML = BAL_PIXELS; return; }
+            el.textContent = fmtAmount(sats);
+        }
         function setHtml(id, html) { const el = document.getElementById(id); if (el) el.innerHTML = html; }
 
         // Classify a peer address the way Umbrel's peers table does.
@@ -1216,12 +1243,22 @@
             const lnRemote = num(cb && ((cb.remote_balance && cb.remote_balance.sat) ?? 0));
             const lnPending = num(cb && ((cb.pending_open_local_balance && cb.pending_open_local_balance.sat) ?? 0));
 
-            setText('balTotal', fmtAmount(onchainConfirmed + lnLocal));
-            setText('balTotalSub', state.onchain || cb ? 'on-chain + lightning' : 'balances unavailable');
-            setText('balLightning', fmtAmount(lnLocal));
-            setText('balLightningSub', lnPending > 0 ? fmtAmount(lnPending) + ' pending open' : 'spendable over channels');
-            setText('balOnchain', fmtAmount(onchainConfirmed));
-            setText('balOnchainSub', onchainUnconfirmed > 0 ? fmtAmount(onchainUnconfirmed) + ' unconfirmed' : 'confirmed');
+            // This function runs on every poll, including before the first
+            // response lands — at which point `state.onchain`/`state.chanbal`
+            // are still null and every figure below computed to 0. The tiles
+            // therefore claimed a zero balance on load. A rail with no data
+            // yet gets the pixel readout instead.
+            const haveOnchain = !!state.onchain;
+            const haveChan = !!cb;
+
+            setBalance('balTotal', haveOnchain || haveChan ? onchainConfirmed + lnLocal : null);
+            setText('balTotalSub', haveOnchain || haveChan ? 'on-chain + lightning' : 'waiting for LND');
+            setBalance('balLightning', haveChan ? lnLocal : null);
+            setText('balLightningSub', !haveChan ? 'waiting for LND'
+                : lnPending > 0 ? fmtAmount(lnPending) + ' pending open' : 'spendable over channels');
+            setBalance('balOnchain', haveOnchain ? onchainConfirmed : null);
+            setText('balOnchainSub', !haveOnchain ? 'waiting for LND'
+                : onchainUnconfirmed > 0 ? fmtAmount(onchainUnconfirmed) + ' unconfirmed' : 'confirmed');
 
             setText('liqLocal', fmtAmount(lnLocal));
             setText('liqRemote', fmtAmount(lnRemote));