feat(ios): replace embedded website with initial native SwiftUI API client

Introduce real SwiftUI auth/dashboard/task/note/shopping screens, a bounded origin-bound URLSession transport and Keychain-backed native sessions. Archive the rejected WebKit renderer rather than embedding it for unfinished modules. Sixteen portable URL/contract/transport tests and Swift format/parsing pass on Linux; Apple SDK application and UI validation remains mandatory. This is an incomplete native slice, not full PWA parity or a release.

legacy/ios/BrowserModelTests.swift

@@ -0,0 +1,40 @@
+import WebKit
+import XCTest
+
+@testable import Yuvomi
+
+final class BrowserModelTests: XCTestCase {
+    @MainActor
+    func testMainViewHasNoNativeBridgeOrAutomaticPopupAccess() {
+        let model = BrowserModel()
+        XCTAssertFalse(model.web.configuration.preferences.javaScriptCanOpenWindowsAutomatically)
+        XCTAssertTrue(model.web.configuration.userContentController.userScripts.isEmpty)
+        XCTAssertTrue(model.web.configuration.websiteDataStore.isPersistent)
+        XCTAssertFalse(model.web.isInspectable)
+    }
+
+    @MainActor
+    func testLateExportCancellationDoesNotEraseAnotherServersDownload() {
+        let model = BrowserModel()
+        let previous = URL(fileURLWithPath: "/old-selection.txt")
+        let current = URL(fileURLWithPath: "/new-selection.txt")
+        model.download = WebDestination(url: current)
+        model.removeDownload(expected: previous)
+        XCTAssertEqual(model.download?.url, current)
+        model.removeDownload(expected: current)
+        XCTAssertNil(model.download)
+    }
+
+    @MainActor
+    func testServerErasureReplacesHistoryContext() async {
+        let model = BrowserModel()
+        let previousView = model.web
+        await withCheckedContinuation { continuation in
+            model.erase { continuation.resume() }
+        }
+        XCTAssertFalse(previousView === model.web)
+        XCTAssertNil(model.server)
+        XCTAssertFalse(model.canGoBack)
+        XCTAssertNil(model.error)
+    }
+}