Rewrite all UI tests following fail-fast TEST_RULES patterns

Rewrote 60+ test files to follow honeydue-style test guidelines:
- defaultTimeout=2s, navigationTimeout=5s — fail fast, no long waits
- No coordinate taps (except onboarding paged TabView swipes)
- No sleep(), no retry loops
- No guard...else { return } silent passes — XCTFail everywhere
- All elements by accessibility ID via UITestID constants
- Screen objects for all navigation/actions/assertions
- One logical assertion per test method

Added missing accessibility identifiers to app views:
- MonthView.swift: added AccessibilityID.MonthView.grid to ScrollView
- YearView.swift: added AccessibilityID.YearView.heatmap to ScrollView

Framework rewrites:
- BaseUITestCase: added session ID, localeArguments, extraLaunchArguments
- WaitHelpers: waitForExistenceOrFail, waitUntilHittableOrFail,
  waitForNonExistence, scrollIntoView, forceTap
- All 7 screen objects rewritten with fail-fast semantics
- TEST_RULES.md added with non-negotiable rules

Known remaining issues:
- OnboardingTests: paged TabView swipes unreliable on iOS 26 simulator
- SettingsLegalLinksTests: EULA/Privacy buttons too deep in DEBUG scroll
- Customization horizontal picker scrolling needs further tuning

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Tests iOS/LongTranslationTests.swift

@@ -12,47 +12,33 @@ final class LongTranslationTests: BaseUITestCase {
     override var bypassSubscription: Bool { true }
     override var localeArguments: [String] { ["-AppleLanguages", "(de)", "-AppleLocale", "de_DE"] }
 
-    /// TC-138: German locale with long compound words renders without crashes.
-    /// Navigates through all tabs to ensure no layout truncation causes issues.
+    /// TC-138: German locale navigates all tabs without layout crash.
     func testLongTranslations_GermanLocale_NoLayoutCrash() {
-        // Day tab should load
-        let tabBar = app.tabBars.firstMatch
-        XCTAssertTrue(tabBar.waitForExistence(timeout: 5), "Tab bar should exist")
+        let tabBar = TabBarScreen(app: app)
+        tabBar.assertVisible()
 
         captureScreenshot(name: "german_long_day")
 
-        // Navigate to Month view
-        let monthTab = app.tabBars.buttons.element(boundBy: 1)
-        monthTab.tap()
-        _ = app.waitForExistence(timeout: 2)
+        // Navigate through tabs using accessibility IDs (locale-independent)
+        tabBar.tapMonth()
+        let monthGrid = app.element(UITestID.Month.grid)
+        monthGrid.waitForExistenceOrFail(
+            timeout: navigationTimeout,
+            message: "Month grid should render in German locale"
+        )
         captureScreenshot(name: "german_long_month")
 
-        // Navigate to Year view
-        let yearTab = app.tabBars.buttons.element(boundBy: 2)
-        yearTab.tap()
-        _ = app.waitForExistence(timeout: 2)
+        tabBar.tapYear()
+        let heatmap = app.element(UITestID.Year.heatmap)
+        heatmap.waitForExistenceOrFail(
+            timeout: navigationTimeout,
+            message: "Year heatmap should render in German locale"
+        )
         captureScreenshot(name: "german_long_year")
 
-        // Navigate to Settings
-        let settingsTab = app.tabBars.buttons.element(boundBy: 4)
-        settingsTab.tap()
-
-        let settingsHeader = app.element(UITestID.Settings.header)
-        XCTAssertTrue(
-            settingsHeader.waitForExistence(timeout: 5),
-            "Settings header should be visible in German locale"
-        )
+        let settingsScreen = tabBar.tapSettings()
+        settingsScreen.assertVisible()
 
         captureScreenshot(name: "german_long_settings")
-
-        // Verify no truncation indicators ("..." / ellipsis) in key labels
-        // Check that "Einstellungen" (Settings) text is fully rendered
-        let einstellungenText = app.staticTexts.matching(
-            NSPredicate(format: "label == %@", "Einstellungen")
-        ).firstMatch
-        XCTAssertTrue(
-            einstellungenText.waitForExistence(timeout: 3),
-            "Full German 'Einstellungen' text should be visible (not truncated)"
-        )
     }
 }