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/SettingsActionTests.swift

@@ -11,49 +11,36 @@ final class SettingsActionTests: BaseUITestCase {
     override var seedFixture: String? { "week_of_moods" }
     override var bypassSubscription: Bool { true }
 
-    /// TC-063 / TC-160: Navigate to Settings, clear all data, verify entries are gone.
+    /// TC-063 / TC-160: Navigate to Settings, clear all data, verify app remains usable.
     func testClearData_RemovesAllEntries() {
-        // First verify we have data
-        let entryRow = app.firstEntryRow
-        XCTAssertTrue(
-            entryRow.waitForExistence(timeout: 5),
-            "Entry rows should exist before clearing"
-        )
+        // Verify we have data before clearing
+        let dayScreen = DayScreen(app: app)
+        dayScreen.assertAnyEntryExists()
 
-        // Navigate to Settings tab
+        // Navigate to Settings > Settings sub-tab
         let tabBar = TabBarScreen(app: app)
         let settingsScreen = tabBar.tapSettings()
         settingsScreen.assertVisible()
-
-        // Switch to Settings sub-tab (not Customize)
         settingsScreen.tapSettingsTab()
 
-        // Scroll down to find Clear All Data (it's in the DEBUG section at the bottom)
-        guard settingsScreen.clearDataButton.waitForExistence(timeout: 2) ||
-                app.swipeUntilExists(settingsScreen.clearDataButton, direction: .up, maxSwipes: 6) else {
-            // In non-DEBUG builds, clear data might not be visible
-            // Skip test gracefully
-            return
-        }
-
+        // Scroll to and tap Clear All Data
+        settingsScreen.clearDataButton
+            .scrollIntoView(in: app.scrollViews.firstMatch, direction: .up)
         settingsScreen.tapClearData()
 
-        // Give SwiftData time to propagate the deletion before navigating
-        _ = app.waitForExistence(timeout: 2.0)
-
         // Navigate back to Day tab
         tabBar.tapDay()
 
-        // App should remain usable after clearing data.
-        // After a full clear, Day view may show mood header, entry rows, or empty state.
-        let hasEntry = app.firstEntryRow.waitForExistence(timeout: 10)
-        let hasMoodHeader = app.element(UITestID.Day.moodHeader).waitForExistence(timeout: 2)
-        let hasEmptyState = app.element(UITestID.Day.emptyStateNoData).waitForExistence(timeout: 2)
-        XCTAssertTrue(hasEntry || hasMoodHeader || hasEmptyState,
-            "Day view should show entries, mood header, or empty state after clearing data")
+        // App should remain usable: mood header, entries, or empty state visible
+        let moodHeader = app.element(UITestID.Day.moodHeader)
+        let emptyState = app.element(UITestID.Day.emptyStateNoData)
+        let entryRow = app.firstEntryRow
 
-        // Clear action should not crash the app.
-        XCTAssertTrue(app.tabBars.firstMatch.exists, "App should remain responsive after clearing data")
+        let anyVisible = moodHeader.waitForExistence(timeout: navigationTimeout)
+            || emptyState.waitForExistence(timeout: defaultTimeout)
+            || entryRow.waitForExistence(timeout: defaultTimeout)
+
+        XCTAssertTrue(anyVisible, "Day view should show mood header, entries, or empty state after clearing data")
 
         captureScreenshot(name: "data_cleared")
     }
@@ -63,19 +50,11 @@ final class SettingsActionTests: BaseUITestCase {
         let tabBar = TabBarScreen(app: app)
         let settingsScreen = tabBar.tapSettings()
         settingsScreen.assertVisible()
-
-        // Switch to Settings sub-tab
         settingsScreen.tapSettingsTab()
 
-        // Find the analytics toggle
-        guard settingsScreen.analyticsToggle.waitForExistence(timeout: 2) ||
-                app.swipeUntilExists(settingsScreen.analyticsToggle, direction: .up, maxSwipes: 6) else {
-            // Toggle may not be visible depending on scroll position
-            captureScreenshot(name: "analytics_toggle_not_found")
-            return
-        }
-
-        // Tap the toggle
+        // Scroll to analytics toggle and tap it
+        settingsScreen.analyticsToggle
+            .scrollIntoView(in: app.scrollViews.firstMatch, direction: .up)
         settingsScreen.tapAnalyticsToggle()
 
         captureScreenshot(name: "analytics_toggled")