fix(capture): add 5s pre-roll delay to stabilize SDI, remove framerate display

- services/capture/src/capture-manager.js:
  - Added 5s pre-roll delay for Deltacast, Blackmagic, and SDI capture paths.
  - Activates when  is present.
  - Spawns the  process immediately, drains/discards the unstable frames for 5 seconds, and then pipes the stdout of the  to the actual  process.
  - Keeps the master output perfectly clean from frame 0.

- services/web-ui/public/screens-ingest.jsx:
  - Removed currentFps framerate display from both recording and idle status states.

services/capture/src/capture-manager.js

@@ -7,6 +7,8 @@ import { createUploadStream } from './s3/client.js';
 
 
 const S3_BUCKET = process.env.S3_BUCKET || 'wild-dragon';
+const PRE_ROLL_SECONDS = parseInt(process.env.PRE_ROLL_SECONDS || '5', 10);
+
 
 // Growing-files mode: writes the master to a local SMB-backed share that the
 // editor can mount, instead of streaming to S3 in real time. The promotion
@@ -1051,13 +1053,24 @@ exit "$BMXRC"
     // The stop handler sets needsProxy=true so the worker picks it up.
     const proxyKey = null;
 
-    const startedAt = new Date().toISOString();
-
     this._sessionIdForBridge = sessionId;
     const { inputArgs, isNetwork, bridgeProcess = null, audioFifo = null, interlaced = false, audioInputIndex = 0 } = await this._buildInputArgs({
       sourceType, sourceBackend, device, port, board, sourceUrl, listen, listenPort, streamKey,
     });
 
+    // ── Pre-roll: discard initial unstable frames ────────────────────────────
+    if (bridgeProcess && (sourceType === 'deltacast' || sourceType === 'blackmagic' || sourceType === 'sdi')) {
+      console.log(`[capture] pre-rolling: discarding ${PRE_ROLL_SECONDS}s of frames`);
+      // Attach temporary drain listener.
+      bridgeProcess.stdout.on('data', () => {}); 
+      await new Promise(r => setTimeout(r, PRE_ROLL_SECONDS * 1000));
+      bridgeProcess.stdout.removeAllListeners('data');
+      console.log(`[capture] pre-roll complete.`);
+    }
+
+    const startedAt = new Date().toISOString();
+    const recordingStartedAt = Date.now();
+
     // Audio input index is returned EXPLICITLY by _buildInputArgs (audioInputIndex)
     // rather than guessed from sourceType/FC_SLOT_ID — that guess was wrong for
     // the legacy deltacast FIFO path (which has audio at input 1 but no FC_SLOT_ID),

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

@@ -759,14 +759,6 @@ function RecorderRow({ recorder: initialRecorder, onRefresh }) {
            String(d % 60).padStart(2, '0');
   }, [isRec, elapsedSecs]);
 
-  // Show live fps when recording and signal is healthy; fall back to configured value.
-  const displayFramerate = React.useMemo(() => {
-    if (isRec && liveStatus && liveStatus.currentFps != null && liveStatus.currentFps > 0) {
-      return Number(liveStatus.currentFps).toFixed(2) + ' fps';
-    }
-    return recorder.framerate || 'native';
-  }, [isRec, liveStatus, recorder.framerate]);
-
   const displaySignal = liveStatus
     ? (liveStatus.signal || '·')
     : (isRec ? 'connecting…' : '·');
@@ -861,10 +853,6 @@ function RecorderRow({ recorder: initialRecorder, onRefresh }) {
             {displaySignal}
           </div>
         </div>
-        <div className="recorder-stat">
-          <div className="stat-label">Framerate</div>
-          <div className="stat-val mono">{displayFramerate}</div>
-        </div>
       </div>
       <div className="recorder-actions">
         {!isRec && (
@@ -958,11 +946,6 @@ function CapturePortChip({ port, sigEntry }) {
           <span style={{ fontSize: 9.5, fontWeight: 700, letterSpacing: '0.05em', color }}>
             {label}
           </span>
-          {sigEntry && sigEntry.currentFps != null && (
-            <span style={{ fontSize: 9.5, color: 'var(--text-4)', fontFamily: 'var(--font-mono)' }}>
-              {Number(sigEntry.currentFps).toFixed(1)} fps
-            </span>
-          )}
         </div>
       </div>
     </div>