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>

PlantGuideUITests/README.md

@@ -0,0 +1,49 @@
+# PlantGuide UI Tests
+
+## Quick Start
+
+```bash
+# Compile only (no device required)
+xcodebuild build-for-testing \
+  -project PlantGuide.xcodeproj \
+  -scheme PlantGuide \
+  -destination 'platform=iOS Simulator,name=iPhone 17'
+
+# Run all UI tests
+xcodebuild test \
+  -project PlantGuide.xcodeproj \
+  -scheme PlantGuide \
+  -destination 'platform=iOS Simulator,name=iPhone 17' \
+  -only-testing:PlantGuideUITests
+```
+
+## Directory Layout
+
+```
+PlantGuideUITests/
+  Foundation/          # Shared infrastructure
+    BaseUITestCase     # Base class for all tests
+    UITestID           # Accessibility identifier constants
+    WaitHelpers        # Predicate-based waits (no sleep!)
+  Helpers/
+    LaunchConfigKey    # Launch arg/env constants
+  Screens/             # Page objects
+    TabBarScreen
+    CameraScreen
+    CollectionScreen
+    TodayScreen
+    SettingsScreen
+    PlantDetailScreen
+```
+
+## Conventions
+
+- Inherit `BaseUITestCase`, not `XCTestCase`
+- Use `UITestID.*` identifiers, not localized strings
+- Use screen objects for element access and assertions
+- Launch with `launchClean()`, `launchWithMockData()`, or `launchOffline()`
+- Replace `sleep()` with `waitUntilHittable()` / `waitUntilGone()` / `waitForExistence(timeout:)`
+
+## Adding a Test
+
+See [Docs/XCUITest-Authoring.md](../Docs/XCUITest-Authoring.md) for full guide.