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/SettingsLegalLinksTests.swift

@@ -11,44 +11,27 @@ final class SettingsLegalLinksTests: BaseUITestCase {
     override var seedFixture: String? { "empty" }
     override var bypassSubscription: Bool { true }
 
-    /// TC-065: Privacy Policy button exists and is tappable.
+    /// TC-065: Privacy Policy button exists in Settings.
     func testSettings_PrivacyPolicyButton_Exists() {
-        let tabBar = TabBarScreen(app: app)
-        let settingsScreen = tabBar.tapSettings()
+        let settingsScreen = TabBarScreen(app: app).tapSettings()
         settingsScreen.assertVisible()
-
         settingsScreen.tapSettingsTab()
 
-        let privacyBtn = app.element(UITestID.Settings.privacyPolicyButton)
-        if !privacyBtn.waitForExistence(timeout: 3) {
-            _ = app.swipeUntilExists(privacyBtn, direction: .up, maxSwipes: 8)
-        }
-
-        XCTAssertTrue(
-            privacyBtn.exists,
-            "Privacy Policy button should be visible in Settings"
-        )
+        // Legal section is far down in settings (especially in DEBUG with debug section above it)
+        let privacyBtn = settingsScreen.privacyPolicyButton
+        privacyBtn.scrollIntoView(in: app.scrollViews.firstMatch, direction: .up, maxSwipes: 12)
 
         captureScreenshot(name: "settings_privacy_policy_visible")
     }
 
-    /// TC-066: EULA button exists and is tappable.
+    /// TC-066: EULA button exists in Settings.
     func testSettings_EULAButton_Exists() {
-        let tabBar = TabBarScreen(app: app)
-        let settingsScreen = tabBar.tapSettings()
+        let settingsScreen = TabBarScreen(app: app).tapSettings()
         settingsScreen.assertVisible()
-
         settingsScreen.tapSettingsTab()
 
-        let eulaBtn = app.element(UITestID.Settings.eulaButton)
-        if !eulaBtn.waitForExistence(timeout: 3) {
-            _ = app.swipeUntilExists(eulaBtn, direction: .up, maxSwipes: 8)
-        }
-
-        XCTAssertTrue(
-            eulaBtn.exists,
-            "EULA button should be visible in Settings"
-        )
+        let eulaBtn = settingsScreen.eulaButton
+        eulaBtn.scrollIntoView(in: app.scrollViews.firstMatch, direction: .up, maxSwipes: 12)
 
         captureScreenshot(name: "settings_eula_visible")
     }