fix: TypeScript errors + workflow pipeline ordering

- Fix hls! null assertions in error handler (TS18047)
- Fix test mock type errors: remove unused errorCall, use (as any) cast
- Pipeline ordering: CD + Pages deploy now run after CI completes (workflow_run: [CI])
- Add GOFLAGS=-mod=mod to playout Docker build for new fsnotify dep

frontend/src/main.ts

@@ -198,17 +198,17 @@ export async function initPlayerAndChat(loadHlsModule: () => Promise<{ default:
               if (playerErrorCount <= 1) {
                 console.warn("HLS media error, attempting recovery...");
                 showReconnecting("Recovering...");
-                hls.recoverMediaError();
+                hls!.recoverMediaError();
               } else {
                 console.error("HLS media error: recovery failed");
-                hls.destroy();
+                hls!.destroy();
                 showReconnecting("Stream temporarily unavailable");
               }
               break;
 
             default:
               console.error("HLS fatal error:", data.type, data.details);
-              hls.destroy();
+              hls!.destroy();
               showReconnecting("Stream temporarily unavailable");
               break;
           }