fix: settings S3 surfaces fetch errors; recorder signal dot pulses

- screens-admin.jsx S3SettingsCard: when /settings/s3 fails, log to
  console and surface the message in the existing SettingsMsg banner
  instead of silently returning empty fields. Also logs the response
  payload on success so the next "endpoint blank" report is easier to
  diagnose. (closes part of #15)
- screens-ingest.jsx recorder row: wrap the signal value in a dot+text
  pair; add CSS so the dot pulses green when status=receiving and
  matches the value color otherwise. The pulse is the kind of cue the
  Live signal column was missing per #2.

services/web-ui/public/screens-admin.jsx

@@ -1235,11 +1235,25 @@ function S3SettingsCard() {
   React.useEffect(() => {
     window.ZAMPP_API.fetch('/settings/s3')
       .then(data => {
-        setS3({ s3_endpoint: data.s3_endpoint || '', s3_bucket: data.s3_bucket || '', s3_access_key: data.s3_access_key || '', s3_secret_key: '', s3_region: data.s3_region || 'us-east-1' });
+        // Diagnostic: previous reports of "endpoint always blank" were
+        // hard to chase without seeing the raw payload. Log it once on
+        // load so the next user can verify quickly.
+        try { console.debug('[settings] /settings/s3 →', data); } catch (_) {}
+        setS3({
+          s3_endpoint:   data.s3_endpoint   || '',
+          s3_bucket:     data.s3_bucket     || '',
+          s3_access_key: data.s3_access_key || '',
+          s3_secret_key: '',
+          s3_region:     data.s3_region     || 'us-east-1',
+        });
         setSecretExists(!!data.s3_secret_key_exists);
         setLoading(false);
       })
-      .catch(() => setLoading(false));
+      .catch(err => {
+        console.error('[settings] /settings/s3 failed:', err);
+        setMsg({ ok: false, text: 'Could not load S3 settings: ' + (err.message || err) });
+        setLoading(false);
+      });
   }, []);
 
   const save = () => {

services/web-ui/public/screens-ingest.jsx

@@ -413,7 +413,10 @@ function RecorderRow({ recorder: initialRecorder, onRefresh }) {
         </div>
         <div className="recorder-stat">
           <div className="stat-label">Signal</div>
-          <div className="stat-val" style={{ fontSize: 11, color: signalColor }}>{displaySignal}</div>
+          <div className="stat-val signal-val" style={{ fontSize: 11, color: signalColor }}>
+            <span className={'signal-dot ' + displaySignal} style={{ background: signalColor }} />
+            {displaySignal}
+          </div>
         </div>
         {liveStatus?.currentFps != null && (
           <div className="recorder-stat">

services/web-ui/public/styles-fixes.css

@@ -517,3 +517,27 @@
   box-shadow: 0 0 0 3px var(--live-soft);
   animation: pulse 1.6s ease-in-out infinite;
 }
+
+/* ============================================================
+   Recorder row — signal indicator with a pulsing dot when
+   actually receiving frames. Closes part of #2.
+   ============================================================ */
+.signal-val {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+}
+.signal-dot {
+  width: 6px;
+  height: 6px;
+  border-radius: 50%;
+  flex-shrink: 0;
+  box-shadow: 0 0 0 2px rgba(255, 255, 255, 0.04);
+}
+.signal-dot.receiving {
+  animation: signalPulse 1.4s ease-in-out infinite;
+}
+@keyframes signalPulse {
+  0%, 100% { box-shadow: 0 0 0 0 rgba(45, 212, 168, 0.6); }
+  50%      { box-shadow: 0 0 0 6px rgba(45, 212, 168, 0); }
+}