fix(lib): remove excess pakfileentry buffer padding

Buffer is derived from a resizable MemoryStream buffer, so gets padded
up. For text data, this results in a bunch of a NULs. Buffer is readonly
unless replaced entirely, so we can just limit it to the size of the
uncompressed zip data.

src/Lumper.Lib/BSP/Struct/PakFileEntry.cs

@@ -74,7 +74,7 @@ public ReadOnlySpan<byte> GetData()
         {
             lock (ZipAccessLock)
             {
-                using var mem = new MemoryStream(); // Note MemoryStream disposal doesn't delete underlying buffer
+                using var mem = new MemoryStream((int)ZipEntry!.Size); // Note MemoryStream disposal doesn't delete underlying buffer
                 using Stream zipStream = ZipEntry!.OpenEntryStream();
                 zipStream.CopyTo(mem);
                 _buffer = mem.GetBuffer();