feat: center square Hope presence and guide secure certificate setup

Sources/Networking/AuthClient.swift

@@ -32,6 +32,17 @@ struct AuthLoginResponse: Decodable {
     }
 
 }
+enum ConnectionFailure {
+    static func message(_ error: Error, server: URL) -> String {
+        let ns = error as NSError
+        let certificateCodes: Set<Int> = [-1200, -1201, -1202, -1203, -1204, -1205, -1206]
+        if ns.domain == NSURLErrorDomain && certificateCodes.contains(ns.code) {
+            return "The certificate for \(server.host ?? "this server") is not trusted. For your private Hope server, install the verified certificate profile in Safari, then enable it in Settings → General → About → Certificate Trust Settings. Do not continue if the server address is unfamiliar."
+        }
+        return error.localizedDescription
+    }
+}
+
 enum AuthError: LocalizedError {
     case status(Int)
     case invalidResponse