fix: switch WebSocket to Tailscale IP, add configurable Orin URL (Issue #709)

- Default URL updated from ws://192.168.86.158:9090 (LAN) to ws://100.64.0.2:9090 (Tailscale)
- URL persisted in UserDefaults under key "orinURL" — survives app restarts
- WebSocketClient.url is now mutable so it can be updated without recreation
- SensorManager.updateURL(_:) applies a new URL when not streaming
- ContentView: editable text field for Orin address with Apply button, disabled while streaming
- Connection banner shows the active URL instead of hardcoded string

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SulTee/SulTee/ContentView.swift

@@ -2,11 +2,15 @@ import SwiftUI
 
 struct ContentView: View {
     @EnvironmentObject var sensor: SensorManager
+    @AppStorage("orinURL") private var orinURL: String = SensorManager.defaultOrinURL
+    @State private var editingURL: String = ""
+    @FocusState private var urlFieldFocused: Bool
 
     var body: some View {
         NavigationStack {
             VStack(spacing: 24) {
                 connectionBanner
+                orinURLField
                 Divider()
                 sensorRatesGrid
                 Divider()
@@ -20,11 +24,41 @@ struct ContentView: View {
             }
             .padding()
             .navigationTitle("Sul-Tee")
+            .onAppear { editingURL = orinURL }
         }
     }
 
     // MARK: - Subviews
 
+    private var orinURLField: some View {
+        VStack(alignment: .leading, spacing: 4) {
+            Text("Orin WebSocket URL")
+                .font(.caption)
+                .foregroundStyle(.secondary)
+            HStack {
+                TextField("ws://host:port", text: $editingURL)
+                    .textFieldStyle(.roundedBorder)
+                    .keyboardType(.URL)
+                    .autocorrectionDisabled()
+                    .textInputAutocapitalization(.never)
+                    .focused($urlFieldFocused)
+                    .disabled(sensor.isStreaming)
+                    .onSubmit { applyURL() }
+                if !sensor.isStreaming {
+                    Button("Apply") { applyURL() }
+                        .buttonStyle(.borderedProminent)
+                        .controlSize(.small)
+                }
+            }
+        }
+    }
+
+    private func applyURL() {
+        urlFieldFocused = false
+        orinURL = editingURL
+        sensor.updateURL(editingURL)
+    }
+
     private var connectionBanner: some View {
         HStack(spacing: 12) {
             Circle()
@@ -102,7 +136,7 @@ struct ContentView: View {
 
     private var wsLabel: String {
         switch sensor.wsState {
-        case .connected:    return "Connected — ws://192.168.86.158:9090"
+        case .connected:    return "Connected — \(orinURL)"
         case .connecting:   return "Connecting…"
         case .disconnected: return "Disconnected"
         }

SulTee/SulTee/SensorManager.swift

@@ -18,7 +18,16 @@ final class SensorManager: NSObject, ObservableObject {
 
     // MARK: - Dependencies
 
-    private let ws = WebSocketClient(url: URL(string: "ws://192.168.86.158:9090")!)
+    static let defaultOrinURL = "ws://100.64.0.2:9090"
+    private static let orinURLKey = "orinURL"
+
+    private(set) var ws: WebSocketClient
+
+    /// Current Orin WebSocket URL string (persisted in UserDefaults).
+    var orinURLString: String {
+        get { UserDefaults.standard.string(forKey: Self.orinURLKey) ?? Self.defaultOrinURL }
+        set { UserDefaults.standard.set(newValue, forKey: Self.orinURLKey) }
+    }
     private let locationManager = CLLocationManager()
     private let motionManager = CMMotionManager()
     private let altimeter = CMAltimeter()
@@ -35,6 +44,8 @@ final class SensorManager: NSObject, ObservableObject {
     // MARK: - Init
 
     override init() {
+        let urlString = UserDefaults.standard.string(forKey: Self.orinURLKey) ?? Self.defaultOrinURL
+        self.ws = WebSocketClient(url: URL(string: urlString) ?? URL(string: Self.defaultOrinURL)!)
         super.init()
         locationManager.delegate = self
         locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation
@@ -69,6 +80,16 @@ final class SensorManager: NSObject, ObservableObject {
         rateTimer = nil
     }
 
+    /// Call when the user edits the Orin URL. Persists the value and updates
+    /// the client URL; takes effect on the next connect().
+    func updateURL(_ urlString: String) {
+        guard !isStreaming else { return }
+        orinURLString = urlString
+        if let url = URL(string: urlString), url.scheme?.hasPrefix("ws") == true {
+            ws.url = url
+        }
+    }
+
     // MARK: - Sensor start / stop
 
     private func requestPermissionsAndStartSensors() {

SulTee/SulTee/WebSocketClient.swift

@@ -11,7 +11,7 @@ final class WebSocketClient: NSObject, ObservableObject {
 
     @Published var state: ConnectionState = .disconnected
 
-    private let url: URL
+    var url: URL
     private var session: URLSession!
     private var task: URLSessionWebSocketTask?
     private var shouldRun = false