Tuner v1: HLS pipeline with playback/ingest modes

FFmpeg -> MediaMTX -> HLS relay with runtime-configurable modes:
- PLAYBACK_MODE: standard (mpegts), fmp4 (HEVC), llhls
- INGEST_MODE: rtmp, rtsp
- INGEST_AUDIO_MODE: aac, copy
- Hourly playlist auto-refresh from upstream URL
- Fullscreen video UI with collapsible sidebar, upstream-down banner
- Same-origin HLS proxy for HTTPS deployments

Tagged as the last HLS-based version before the mpegts.js (v2) rework.

frontend/src/components/StatusBar.tsx

@@ -53,6 +53,12 @@ export default function StatusBar({ status }: Props) {
           </span>
         </>
       )}
+      {status.upstream_down && (
+        <>
+          <span className="status-separator">|</span>
+          <span className="upstream-down-banner">Upstream down?</span>
+        </>
+      )}
       {h && h.speed && (
         <span className="status-health">
           <span className="status-separator">|</span>