Resolve DataStore IOException by checking single instance before Koin (#2044)

[zaibihsn]

When a user launches a second instance of the SimpMusic Desktop app while the first instance is still running in the background, the app crashes with a fatal java.io.IOException (Unable to rename ... settings.preferences_pb.tmp). This is caused by a file-locking collision on Windows because multiple instances of AndroidX DataStore are attempting to access the same preferences file.

Root Cause:
In DesktopApp.kt, startKoin { ... } was being executed before the application checked if it was a single instance (SingleInstanceManager.isSingleInstance). Because Koin initialized the dependency graph immediately, the newly spawned Java process created a duplicate DataStore object. This duplicate DataStore attempted to lock and modify settings.preferences_pb while the original process still held the lock.

Resolution:

Moved the SingleInstanceManager.isSingleInstance() check to the very beginning of the runDesktopApp function, entirely before startKoin is called.

Added a restoreRequest callback to ensure the window state is correctly brought back to the foreground when a duplicate launch is intercepted.

Now, if a second instance is launched, it immediately passes the request and deep links to the running instance and exits before it ever attempts to initialize Koin or touch the DataStore preferences file on disk.

[maxrave-dev]

Create PR after you done, don't spam COMMITs

[zaibihsn]

Completely understand, Max. I apologize for the extra commits; I had some trouble untangling my Git history locally after accidentally including the wrong files. I have submitted a new PR that contains only the single, clean commit pointed at the dev branch. You can review it here: #2091. Thank you for the guidance!