fix(ios): keep transcript rows in sync with environment changes on iOS 27

On iOS 27, SwiftUI re-runs a representable's update only when an
environment value read during it changes; even @Environment(\.self) is
tracked per key. AnchoredTranscriptList copied context.environment
without reading keys, and compared metrics later in a drain that is
often deferred. A theme switch or a system text size change therefore
never reached the hosted rows: text kept its old size and colors.

updateUIViewController now reads every runtime-changing value the rows
follow (Dynamic Type, bold text, typography, locale, direction, color
scheme, theme, link action, enabled state). Rows still receive the
complete environment snapshot.

The tests drive Dynamic Type through UIKit traits, as the system does.
On iOS 27 a SwiftUI dynamicTypeSize override does not reach a UIKit
representable's environment, and the app never sets one above the
list. A new test checks that theme-only and text-size-only changes
reach visible rows without reconfiguring cells; it fails without the
fix.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ios/HapiTests/TranscriptRefreshTests.swift

@@ -25,7 +25,6 @@ final class TranscriptRefreshTests: XCTestCase {
         var version = 0
         var basePath = "/before"
         var dark = false
-        var size = DynamicTypeSize.large
         var locale = Locale(identifier: "en")
         var direction = LayoutDirection.leftToRight
         var actionToken = 0
@@ -41,7 +40,6 @@ final class TranscriptRefreshTests: XCTestCase {
             let token = driver.actionToken
             ListView(driver: driver)
                 .hapiTheme(driver.dark ? .dark : .light)
-                .environment(\.dynamicTypeSize, driver.size)
                 .environment(\.locale, driver.locale)
                 .environment(\.layoutDirection, driver.direction)
                 .environment(\.hapiOpenURL, HapiOpenURLAction { _ in
@@ -95,6 +93,7 @@ final class TranscriptRefreshTests: XCTestCase {
     private func host(_ driver: Driver) throws -> (UIWindow, TranscriptCollectionController<Row>, UICollectionView) {
         let scene = try XCTUnwrap(UIApplication.shared.connectedScenes.compactMap { $0 as? UIWindowScene }.first)
         let window = UIWindow(windowScene: scene)
+        window.setDynamicTypeSize(.large)
         let host = UIHostingController(rootView: Harness(driver: driver))
         window.rootViewController = host
         window.makeKeyAndVisible()
@@ -153,6 +152,28 @@ final class TranscriptRefreshTests: XCTestCase {
         XCTAssertEqual(tail.frame.height, 180, accuracy: 1, "Recycled cells must use the latest offscreen value")
     }
 
+    func testEnvironmentOnlyChangesReachVisibleRows() async throws {
+        let driver = Driver()
+        let (window, controller, view) = try host(driver)
+        defer { window.isHidden = true }
+        await settle { driver.layouts.contains(0) }
+        await browse(view, index: 25)
+        #if DEBUG
+        let configurations = controller.cellConfigurationCount
+        #endif
+        // No item or closure capture changes: only the environment does.
+        driver.dark = true
+        await settle { driver.samples["25"]?.dark == true }
+        XCTAssertEqual(driver.samples["25"]?.dark, true, "A theme change must reach hosted rows")
+        #if DEBUG
+        XCTAssertEqual(controller.cellConfigurationCount, configurations)
+        #endif
+        window.setDynamicTypeSize(.accessibility2)
+        await settle { driver.samples["25"]?.size == .accessibility2 }
+        let cell = try XCTUnwrap(view.cellForItem(at: IndexPath(item: 25, section: 0)))
+        XCTAssertEqual(cell.frame.height, 180, accuracy: 1, "A system text size change must re-measure rows")
+    }
+
     func testEqualItemsReceiveLatestEnvironmentValueCapturesAndActions() async throws {
         let driver = Driver()
         let (window, controller, view) = try host(driver)
@@ -177,7 +198,7 @@ final class TranscriptRefreshTests: XCTestCase {
         // change; only ordinary data/context updates have a zero-config budget.
         driver.locale = Locale(identifier: "ar")
         driver.direction = .rightToLeft
-        driver.size = .accessibility2
+        window.setDynamicTypeSize(.accessibility2)
         let recycled = Sample(basePath: "/after", dark: true, size: .accessibility2, locale: "ar", direction: .rightToLeft)
         await settle { driver.samples["25"] == recycled }
         let cell = try XCTUnwrap(view.cellForItem(at: IndexPath(item: 25, section: 0)))
@@ -186,3 +207,12 @@ final class TranscriptRefreshTests: XCTestCase {
         XCTAssertEqual(driver.samples["60"], recycled)
     }
 }
+
+private extension UIWindow {
+    /// Change text size as the system does. On iOS 27 a SwiftUI
+    /// `dynamicTypeSize` override does not reach a UIKit representable's
+    /// `context.environment`, and the app never overrides it above the list.
+    func setDynamicTypeSize(_ size: DynamicTypeSize) {
+        traitOverrides.preferredContentSizeCategory = UIContentSizeCategory(size)
+    }
+}