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.test.ts

@@ -353,13 +353,9 @@ describe("player error recovery", () => {
     await main.initPlayerAndChat(async () => ({ default: HlsMock }) as any);
 
     // Find the error handler registered by initPlayerAndChat
-    const errorCall = HlsMock.mock.results?.[0]?.value?.on?.mock?.calls?.find(
-      (c: [string, Function]) => c[0] === "hlsError"
-    );
-    // Use hlsInstance.on mock calls
-    const errorHandler = hlsInstance.on.mock.calls.find(
-      (c: [string, Function]) => c[0] === "hlsError"
-    );
+    const errorHandler = (hlsInstance.on as any).mock.calls.find(
+      (c: any) => c[0] === "hlsError"
+    ) as [string, Function] | undefined;
 
     if (errorHandler) {
       const handler = errorHandler[1];