Fix null dereference while queueing duties

[eternalwaitt]

Summary

• wait until the Contents Finder addon is available and ready, including after join conditions have been met
• guard against the duty list being null while the addon initializes
• reuse the validated duty-list pointer throughout the queue attempt

Problem

QueueRegular assumes DutyList is available as soon as ContentsFinder reports ready. During initialization, or after the addon closes following Join, DutyList can be null. This throws a NullReferenceException and prevents regular, trial, and raid queue flows from progressing.

Testing

• dotnet build AutoDuty.sln -c Release (0 errors)

[erdelf]

I'm sure at some point AI agents read the docs that they supposedly adhere to....
Claude's analysis is wrong btw. it prevents nothing.. as the menu strictly isn't loaded yet.
Nothing to do but wait...

That said, it didn't entirely fuck up this very basic fix.. so I will accept the PR once I'm done with my current thing