Rebuild UI test foundation with page objects, wait helpers, and screen objects

Replace brittle localized-string selectors and broken wait helpers with a
robust, identifier-first UI test infrastructure. All 41 UI tests pass on
iOS 26.2 simulator (iPhone 17).

Foundation:
- BaseUITestCase with deterministic launch helpers (launchClean, launchOffline)
- WaitHelpers (waitUntilHittable, waitUntilGone, tapWhenReady) replacing sleep()
- UITestID enum mirroring AccessibilityIdentifiers from the app target
- Screen objects: TabBarScreen, CameraScreen, CollectionScreen, TodayScreen,
  SettingsScreen, PlantDetailScreen

Key fixes:
- Tab navigation uses waitForExistence+tap instead of isHittable (unreliable
  in iOS 26 simulator)
- Tests handle real app state (empty collection, no camera permission)
- Increased timeouts for parallel clone execution
- Added NetworkMonitorProtocol and protocol-typed DI for testability
- Fixed actor-isolation issues in unit test mocks

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

PlantGuideTests/IdentifyPlantOnDeviceUseCaseTests.swift

@@ -264,22 +264,19 @@ final class IdentifyPlantOnDeviceUseCaseTests: XCTestCase {
             }
         }
 
-        // Configure mock to throw
-        let service = mockClassificationService!
-        Task {
-            service.shouldThrowOnClassify = true
-            service.errorToThrow = PlantClassificationError.modelLoadFailed
+        // Configure mock to throw via actor-isolated method
+        await mockClassificationService.setThrowBehavior(
+            shouldThrow: true,
+            error: PlantClassificationError.modelLoadFailed
+        )
+
+        // Verify the error propagates
+        do {
+            _ = try await sut.execute(image: testImage)
+            XCTFail("Expected classification error to be thrown")
+        } catch {
+            XCTAssertNotNil(error)
         }
-
-        // Give time for the configuration to apply
-        try? await Task.sleep(nanoseconds: 10_000_000) // 10ms
-
-        // Note: Due to actor isolation, we need to check this differently
-        // For now, verify the normal path works
-        await mockClassificationService.configureDefaultPredictions()
-
-        let result = try? await sut.execute(image: testImage)
-        XCTAssertNotNil(result)
     }
 
     // MARK: - Error Description Tests