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/OnboardingTests.swift

@@ -12,83 +12,39 @@ final class OnboardingTests: BaseUITestCase {
     override var skipOnboarding: Bool { false }
 
     /// TC-120: Complete the full onboarding flow.
-    func testOnboarding_CompleteFlow() throws {
+    func testOnboarding_CompleteFlow() {
         let onboarding = OnboardingScreen(app: app)
-        XCTAssertTrue(onboarding.welcomeScreen.waitForExistence(timeout: 10), "Welcome screen should appear on first launch")
+        onboarding.assertVisible()
 
         captureScreenshot(name: "onboarding_welcome")
 
-        // Advance through onboarding to the subscription step.
-        XCTAssertTrue(advanceToScreen(onboarding.subscriptionScreen), "Should reach onboarding subscription screen")
-        captureScreenshot(name: "onboarding_time")
-        captureScreenshot(name: "onboarding_day")
-        captureScreenshot(name: "onboarding_style")
-        captureScreenshot(name: "onboarding_subscription")
-        try completeOnboardingOrSkip()
+        onboarding.completeOnboarding()
+        onboarding.assertDismissed()
 
         captureScreenshot(name: "onboarding_complete")
     }
 
     /// TC-121: After completing onboarding, relaunch should go directly to Day view.
-    func testOnboarding_DoesNotRepeatAfterCompletion() throws {
+    func testOnboarding_DoesNotRepeatAfterCompletion() {
         let onboarding = OnboardingScreen(app: app)
+        onboarding.assertVisible()
+        onboarding.completeOnboarding()
+        onboarding.assertDismissed()
 
-        // First launch should show onboarding and allow completion.
-        XCTAssertTrue(
-            onboarding.welcomeScreen.waitForExistence(timeout: 5),
-            "Onboarding should be shown on first launch"
-        )
-        XCTAssertTrue(advanceToScreen(onboarding.subscriptionScreen), "Should reach onboarding subscription screen")
-        try completeOnboardingOrSkip()
-
-        // Relaunch preserving state — onboarding should not repeat.
-        let freshApp = relaunchPreservingState()
+        // Relaunch preserving state -- onboarding should not repeat
+        relaunchPreservingState()
 
         // Tab bar should appear immediately (no onboarding)
-        let freshTabBar = freshApp.tabBars.firstMatch
-        XCTAssertTrue(
-            freshTabBar.waitForExistence(timeout: 10),
-            "Tab bar should appear immediately on relaunch (no onboarding)"
-        )
+        let tabBar = TabBarScreen(app: app)
+        tabBar.assertVisible()
 
         // Welcome screen should NOT appear
-        let welcomeAgain = freshApp.element(UITestID.Onboarding.welcome)
+        let welcomeAgain = app.element(UITestID.Onboarding.welcome)
         XCTAssertFalse(
-            welcomeAgain.waitForExistence(timeout: 2),
+            welcomeAgain.waitForExistence(timeout: defaultTimeout),
             "Onboarding should not appear on second launch"
         )
 
         captureScreenshot(name: "no_onboarding_on_relaunch")
     }
-
-    /// Swipe left with a brief wait for the page transition to settle.
-    /// Uses a coordinate-based swipe for more reliable page advancement in paged TabView.
-    private func swipeAndWait() {
-        // Swipe near the top to avoid controls (DatePicker/ScrollView) stealing gestures.
-        let start = app.coordinate(withNormalizedOffset: CGVector(dx: 0.9, dy: 0.18))
-        let end = app.coordinate(withNormalizedOffset: CGVector(dx: 0.1, dy: 0.18))
-        start.press(forDuration: 0.05, thenDragTo: end)
-        // Allow the paged TabView animation to settle
-        _ = app.waitForExistence(timeout: 1.0)
-    }
-
-    private func completeOnboardingOrSkip() throws {
-        // Coordinate tap near the bottom center where "Maybe Later" is rendered.
-        app.coordinate(withNormalizedOffset: CGVector(dx: 0.5, dy: 0.92)).tap()
-
-        let tabBar = app.tabBars.firstMatch
-        if !tabBar.waitForExistence(timeout: 10) {
-            throw XCTSkip("Onboarding completion CTA is not reliably exposed in simulator automation")
-        }
-    }
-
-    @discardableResult
-    private func advanceToScreen(_ screen: XCUIElement, maxSwipes: Int = 8) -> Bool {
-        if screen.waitForExistence(timeout: 2) { return true }
-        for _ in 0..<maxSwipes {
-            swipeAndWait()
-            if screen.waitForExistence(timeout: 1.5) { return true }
-        }
-        return false
-    }
 }