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/PersonalityPackTests.swift

@@ -11,40 +11,39 @@ final class PersonalityPackTests: BaseUITestCase {
     override var seedFixture: String? { "single_mood" }
     override var bypassSubscription: Bool { true }
 
-    /// TC-052: Selecting a different personality pack updates the checkmark.
+    /// TC-052: Selecting Coach personality pack renders without crash.
     func testPersonalityPack_SelectCoach() {
-        let tabBar = TabBarScreen(app: app)
-        let settingsScreen = tabBar.tapSettings()
+        let settingsScreen = TabBarScreen(app: app).tapSettings()
         settingsScreen.assertVisible()
         settingsScreen.tapCustomizeTab()
 
         let customizeScreen = CustomizeScreen(app: app)
-
-        // Scroll down to personality pack section and select "Coach"
         customizeScreen.selectPersonalityPack("Coach")
 
-        // Verify the Coach button is now selected — checkmark image should appear
-        let checkmark = app.images.matching(
-            NSPredicate(format: "label CONTAINS 'checkmark'")
-        ).firstMatch
-
-        // The Coach pack button should exist and the checkmark should be near it
-        let coachButton = customizeScreen.personalityPackButton(named: "Coach")
-        XCTAssertTrue(
-            coachButton.exists,
-            "Coach personality pack button should still be visible after selection"
-        )
+        // Verify the Coach button still exists after selection
+        customizeScreen.personalityPackButton(named: "Coach")
+            .waitForExistenceOrFail(
+                timeout: defaultTimeout,
+                message: "Coach personality pack button should be visible after selection"
+            )
 
         captureScreenshot(name: "personality_pack_coach_selected")
+    }
 
-        // Switch to a different pack to verify we can cycle
+    /// TC-052: Switching between personality packs works without crash.
+    func testPersonalityPack_SwitchToZen() {
+        let settingsScreen = TabBarScreen(app: app).tapSettings()
+        settingsScreen.assertVisible()
+        settingsScreen.tapCustomizeTab()
+
+        let customizeScreen = CustomizeScreen(app: app)
         customizeScreen.selectPersonalityPack("Zen")
 
-        let zenButton = customizeScreen.personalityPackButton(named: "Zen")
-        XCTAssertTrue(
-            zenButton.exists,
-            "Zen personality pack button should be visible after selection"
-        )
+        customizeScreen.personalityPackButton(named: "Zen")
+            .waitForExistenceOrFail(
+                timeout: defaultTimeout,
+                message: "Zen personality pack button should be visible after selection"
+            )
 
         captureScreenshot(name: "personality_pack_zen_selected")
     }