style: optimize bitrate rounding logic in inferG726Bitrate

Replaced manual loop with a more reliable reduction method to find the closest supported G.726 bitrate and fixed potential falsy value bugs.

Author: getabalewKemaw

server/src/services/file/FileService.ts

@@ -44,16 +44,13 @@ const inferChannels = (codec?: AudioCodec): ChannelConfig | undefined => {
 };
 
 const inferG726Bitrate = (bitrate?: number | null): number | undefined => {
-    if (!bitrate || !Number.isFinite(bitrate)) return 32;
+
+    if (bitrate===null ||bitrate===undefined || !Number.isFinite(bitrate)){
+        return 32;
+    } 
     const kbps = bitrate >= 1000 ? Math.round(bitrate / 1000) : bitrate;
     const supported = [16, 24, 32,40];
-    let closest = supported[0]!;
-    for (const value of supported) {
-        if (Math.abs(value - kbps) < Math.abs(closest - kbps)) {
-            closest = value;
-        }
-    }
-    return closest;
+    return supported.reduce((prev,curr)=>Math.abs(curr-kbps)< Math.abs(prev-kbps)?curr:prev);
 };
 
 const buildDecodedOutputPath = (filename: string): string => {