feat: add native local location capture (#4)

Add explicit permission handling, independent continuous and single capture,
location status and deterministic CI coverage.

Final decisions and validation:
https://github.com/jayanezj/traccar-client-macos/issues/4#issuecomment-6399189792

TraccarClient/Location/LocationTypes.swift

@@ -0,0 +1,102 @@
+import CoreLocation
+import Foundation
+
+enum LocationPermission: String {
+    case notDetermined = "Not requested"
+    case authorized = "Authorized"
+    case denied = "Denied"
+    case restricted = "Restricted"
+
+    init(_ status: CLAuthorizationStatus) {
+        switch status {
+        case .authorizedAlways: self = .authorized
+        case .notDetermined: self = .notDetermined
+        case .denied: self = .denied
+        default: self = .restricted
+        }
+    }
+}
+
+enum LocationServices: String {
+    case checking = "Checking"
+    case enabled = "Enabled"
+    case disabled = "Disabled"
+}
+
+struct LocationAvailability: Equatable {
+    var permission: LocationPermission
+    var services: LocationServices
+
+    var canCapture: Bool { permission == .authorized && services == .enabled }
+}
+
+struct LocationFix: Equatable {
+    let latitude: Double
+    let longitude: Double
+    let timestamp: Date
+    let horizontalAccuracy: Double
+    let altitude: Double?
+    let speed: Double?
+    let course: Double?
+
+    init?(_ location: CLLocation) {
+        guard CLLocationCoordinate2DIsValid(location.coordinate),
+              location.horizontalAccuracy.isFinite, location.horizontalAccuracy >= 0,
+              location.timestamp.timeIntervalSinceReferenceDate.isFinite else { return nil }
+        latitude = location.coordinate.latitude
+        longitude = location.coordinate.longitude
+        timestamp = location.timestamp
+        horizontalAccuracy = location.horizontalAccuracy
+        altitude = location.verticalAccuracy >= 0 && location.altitude.isFinite ? location.altitude : nil
+        speed = location.speed >= 0 && location.speed.isFinite ? location.speed : nil
+        course = (0..<360).contains(location.course) && location.course.isFinite ? location.course : nil
+    }
+}
+
+enum LocationFailure: Equatable {
+    case permissionDenied
+    case unavailable
+    case other(Int)
+
+    var message: String {
+        switch self {
+        case .permissionDenied: "Location access is denied. Review Location Services in System Settings."
+        case .unavailable: "No location is available. Try again when Location Services can obtain a fix."
+        case .other(let code): "Location could not be obtained (error \(code))."
+        }
+    }
+}
+
+enum LocationRequestKind { case continuous, single }
+enum LocationFixOrigin: String {
+    case continuous = "Continuous capture"
+    case single = "Single capture"
+    case lastKnown = "Last-known location; no new fix"
+}
+
+enum SingleCaptureStatus: String {
+    case idle = "Idle"
+    case waiting = "Waiting for location"
+    case received = "Location received"
+    case lastKnown = "Last-known location used; no new fix"
+    case failed = "No location obtained"
+    case cancelled = "Cancelled"
+}
+
+enum LocationEvent {
+    case availability(LocationAvailability)
+    case locations(LocationRequestKind, request: Int, fixes: [LocationFix])
+    case failure(LocationRequestKind, request: Int, reason: LocationFailure, fallback: LocationFix?)
+}
+
+@MainActor
+protocol LocationProviding: AnyObject {
+    var availability: LocationAvailability { get }
+    var onEvent: ((LocationEvent) -> Void)? { get set }
+    func refreshAvailability()
+    func requestAuthorization()
+    func startContinuous(accuracy: LocationAccuracy, request: Int)
+    func stopContinuous()
+    func requestSingle(accuracy: LocationAccuracy, request: Int)
+    func cancelSingle()
+}