Fix all SwiftLint violations across codebase

Resolves 130+ violations including deployment target checks, code style issues, and formatting inconsistencies. Adds SwiftLint disable comments for compiler-required availability checks while maintaining deployment target compliance.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

macOS/InstancesSettings.swift

@@ -71,12 +71,8 @@ struct InstancesSettings: View {
                     }
                 }
 
-                if #available(macOS 12.0, *) {
-                    list
-                        .listStyle(.inset(alternatesRowBackgrounds: true))
-                } else {
-                    list
-                }
+                list
+                    .listStyle(.inset(alternatesRowBackgrounds: true))
             }
 
             if selectedInstance != nil, selectedInstance.app.hasFrontendURL {