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/Screens/CollectionScreen.swift

@@ -0,0 +1,53 @@
+//
+//  CollectionScreen.swift
+//  PlantGuideUITests
+//
+//  Screen object for the Collection tab.
+//
+
+import XCTest
+
+struct CollectionScreen {
+    let app: XCUIApplication
+
+    // MARK: - Elements
+
+    var navigationBar: XCUIElement { app.navigationBars["My Plants"] }
+
+    var searchField: XCUIElement { app.searchFields.firstMatch }
+
+    var viewModeToggle: XCUIElement {
+        app.buttons[UITestID.Collection.viewModeToggle]
+    }
+
+    var filterButton: XCUIElement {
+        app.buttons[UITestID.Collection.filterButton]
+    }
+
+    var emptyStateView: XCUIElement {
+        app.otherElements[UITestID.Collection.emptyStateView]
+    }
+
+    var scrollView: XCUIElement { app.scrollViews.firstMatch }
+
+    var tableView: XCUIElement { app.tables.firstMatch }
+
+    // MARK: - State Checks
+
+    @discardableResult
+    func waitForLoad(timeout: TimeInterval = 10) -> Bool {
+        navigationBar.waitForExistence(timeout: timeout)
+    }
+
+    var hasPlants: Bool {
+        scrollView.exists || tableView.exists
+    }
+
+    // MARK: - Actions
+
+    func search(_ text: String) {
+        XCTAssertTrue(searchField.waitForExistence(timeout: 5), "Search field missing")
+        searchField.tap()
+        searchField.typeText(text)
+    }
+}