Change file size limit to 512 KiB.

src/cgi.cpp

@@ -70,13 +70,13 @@ entry_type parse_formdata()
 
     for (const auto &screenshot : cgi.getFiles())
     {
-        constexpr size_t size_limit{1024 * 1024 * 1};
+        constexpr size_t size_limit{1024 * 512};
         if (screenshot.getDataLength() > size_limit)
         {
             throw runtime_error{format("The screenshot “{0:s}” is too big. "
-                                       "The limit is {1:.1f} MiB.",
+                                       "The limit is {1:.1f} kilobyte (KiB).",
                                        screenshot.getFilename(),
-                                       size_limit / 1024.0 / 1024)};
+                                       size_limit / 1024.0)};
         }
 
         const string filepath{files::get_tmpdir() / screenshot.getFilename()};