Improve mod update check accuracy (#2385)

* Index API response into lookup maps

* extract new findLatestActiveSuccessor method from update check function

* extract method to check if a file is active

* use new isActiveFileStatus in modInfoRegular

* fix bug when merging during mod install

* remember ordering of installed nexus file ids

* refactor update check logic to prioritize Nexus file IDs over filenames

* refactor nxmUpdatesAvailable to simplify update checking logic

* refactor update check logic to find Nexus file IDs by filename and streamline successor retrieval

* refactor update checking to streamline version resolution and improve successor retrieval

1 files changed, 2 insertions, 1 deletions

diff --git a/src/installationmanager.cpp b/src/installationmanager.cpp
index 37c86c7e..87c4681f 100644
--- a/src/installationmanager.cpp
+++ b/src/installationmanager.cpp
@@ -491,13 +491,14 @@ InstallationResult InstallationManager::doInstall(GuessedValue<QString>& modName
     return {IPluginInstaller::RESULT_FAILED};
   }
 
-  bool merge = false;
   // determine target directory
   InstallationResult result = testOverwrite(modName);
   if (!result) {
     return result;
   }
 
+  const bool merge = result.merged();
+
   result.m_name = modName;
 
   QString targetDirectory       = QDir(m_ModsDirectory + "/" + modName).canonicalPath();