fix(ssr): resolve index.html from production path for CSR shell

The CSR shell path was hardcoded to a local dev directory
(app/server/browser/index.html) which does not exist in the
Docker container. Browser files are copied to /usr/share/nginx/html
by the Dockerfile. browserIndexPath() now checks both production
and development paths, falling back to the first that exists.

server.ts

@@ -25,12 +25,35 @@ const appEngine = new AngularNodeAppEngine();
 
 /**
  * Resolve the static browser index.html path.
- * In the built output the browser files live in the `browser/` subdirectory.
+ *
+ * Production (Docker): browser files are copied to /usr/share/nginx/html/
+ * Local dev (ng build): browser files live in dist/radio-station/browser/
+ * Try each candidate in order and return the first that exists.
  */
 function browserIndexPath(): string {
-  // __dirname in ESM resolves to this file's directory
+  // Production path — Dockerfile copies browser output here
+  const productionPaths = [
+    '/usr/share/nginx/html/index.html',
+    '/var/www/html/index.html',
+  ];
+
+  // Local dev path — relative to the compiled server directory
   const dir = typeof __dirname !== 'undefined' ? __dirname : path.dirname(new URL(import.meta.url).pathname);
-  return path.join(dir, 'browser', 'index.html');
+  const localPaths = [
+    path.join(dir, 'browser', 'index.html'),
+    path.join(dir, '..', 'browser', 'index.html'),
+  ];
+
+  const allCandidates = [...productionPaths, ...localPaths];
+  for (const candidate of allCandidates) {
+    try {
+      if (fs.existsSync(candidate)) return candidate;
+    } catch {
+      // ignore — keep trying
+    }
+  }
+  // Return the first candidate so the error path has a sensible value to log
+  return allCandidates[0];
 }
 
 /**