Fix Swift compilation errors in AI Assistant view controllers

[backdoor-bdg-3]

This PR fixes several Swift compilation errors in the AI Assistant view controllers:

1. In ChatViewController.swift:

   • Fixed all instances of DispatchQueue.main.async(execute: by replacing them with DispatchQueue.main.async

2. In AIViewController.swift:

   • Added the missing frame parameter to the UITableView initializer
   • Fixed the contextual base references by fully qualifying the types
   • Added the override keyword to the refreshContent() method
   • Removed redundant conformance to ViewControllerRefreshable protocol
   • Removed unnecessary try/catch block in loadRecentSessions()

These changes address all the compilation errors while preserving the existing logic.

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