Fix Cmd+? opening Help Book in the default browser instead of Help Viewer

openHelp() always found the bundled oAI.help folder, so it always took
the NSWorkspace.open(index.html) branch — handing the page to the
default web browser. The NSHelpManager branch, which launches the
native Help Viewer (with its built-in full-text search), was
unreachable dead code. Now always routes through NSHelpManager.

oAI/oAIApp.swift

@@ -161,12 +161,7 @@ struct oAIApp: App {
 
     #if os(macOS)
     private func openHelp() {
-        if let helpBookURL = Bundle.main.url(forResource: "oAI.help", withExtension: nil) {
-            NSWorkspace.shared.open(helpBookURL.appendingPathComponent("Contents/Resources/en.lproj/index.html"))
-        } else {
-            // Fallback to Apple Help if help book not found
         NSHelpManager.shared.openHelpAnchor("", inBook: Bundle.main.object(forInfoDictionaryKey: "CFBundleHelpBookName") as? String)
     }
-    }
     #endif
 }