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/YearViewCollapseTests.swift

@@ -16,43 +16,41 @@ final class YearViewCollapseTests: BaseUITestCase {
         let tabBar = TabBarScreen(app: app)
         tabBar.tapYear()
 
-        XCTAssertTrue(tabBar.yearTab.isSelected, "Year tab should be selected")
-
-        // Stats section is visible by default (showStats = true)
+        // Stats section is visible by default
         let statsSection = app.element(UITestID.Year.statsSection)
-        XCTAssertTrue(
-            statsSection.waitForExistence(timeout: 8),
-            "Year stats section should be visible initially"
+        statsSection.waitForExistenceOrFail(
+            timeout: navigationTimeout,
+            message: "Year stats section should be visible initially"
         )
 
         // Find the current year's card header button
         let currentYear = Calendar.current.component(.year, from: Date())
         let headerButton = app.element(UITestID.Year.cardHeader(year: currentYear))
-        XCTAssertTrue(
-            headerButton.waitForExistence(timeout: 5),
-            "Year card header for \(currentYear) should be visible"
+        headerButton.waitUntilHittableOrFail(
+            timeout: navigationTimeout,
+            message: "Year card header for \(currentYear) should be hittable"
         )
 
         captureScreenshot(name: "year_stats_expanded")
 
         // Tap header to collapse stats
-        headerButton.tap()
+        headerButton.forceTap()
 
         // Stats section should disappear
-        XCTAssertTrue(
-            statsSection.waitForDisappearance(timeout: 3),
-            "Stats section should collapse after tapping header"
+        statsSection.waitForNonExistence(
+            timeout: defaultTimeout,
+            message: "Stats section should collapse after tapping header"
         )
 
         captureScreenshot(name: "year_stats_collapsed")
 
         // Tap header again to expand stats
-        headerButton.tap()
+        headerButton.forceTap()
 
         // Stats section should reappear
-        XCTAssertTrue(
-            statsSection.waitForExistence(timeout: 3),
-            "Stats section should expand after tapping header again"
+        statsSection.waitForExistenceOrFail(
+            timeout: defaultTimeout,
+            message: "Stats section should expand after tapping header again"
         )
 
         captureScreenshot(name: "year_stats_re_expanded")