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/ShareNoDataTests.swift

@@ -2,80 +2,44 @@
 //  ShareNoDataTests.swift
 //  Tests iOS
 //
-//  TC-119: Share with no mood data — verifies graceful behavior.
+//  TC-119: Share with no mood data -- verifies graceful behavior.
 //
 
 import XCTest
 
-final class ShareNoDataTests: BaseUITestCase {
+final class ShareNoDataYearTests: BaseUITestCase {
     override var seedFixture: String? { "empty" }
     override var bypassSubscription: Bool { true }
 
-    /// TC-119: With no mood data, Year view share button is absent or sharing handles empty state.
-    func testShare_NoData_GracefulBehavior() {
+    /// TC-119a: With no mood data, Year view share button is absent.
+    func testShare_NoData_YearShareAbsent() {
         let tabBar = TabBarScreen(app: app)
         tabBar.tapYear()
 
-        // Wait for year view to load
-        _ = app.waitForExistence(timeout: 3)
+        // With no data, the share button should not appear
+        let shareButton = app.element(UITestID.Year.shareButton)
+        let shareExists = shareButton.waitForExistence(timeout: defaultTimeout)
+
+        XCTAssertFalse(shareExists, "Year share button should be absent when there is no mood data")
 
         captureScreenshot(name: "share_no_data_year")
-
-        // With no mood data, there should be no year card share button
-        let shareButton = app.element(UITestID.Year.shareButton)
-        let shareExists = shareButton.waitForExistence(timeout: 3)
-
-        if shareExists {
-            // If the share button exists despite no data, tap it and verify
-            // the sharing picker handles empty state gracefully
-            shareButton.tapWhenReady()
-
-            _ = app.waitForExistence(timeout: 2)
-
-            captureScreenshot(name: "share_no_data_picker")
-
-            // Look for "No designs available" text or a valid picker
-            let noDesigns = app.staticTexts["No designs available"].firstMatch
-            let exitButton = app.buttons["Exit"].firstMatch
-            let pickerPresent = noDesigns.waitForExistence(timeout: 3) ||
-                exitButton.waitForExistence(timeout: 3)
-
-            // Either the picker shows empty state or renders normally
-            // Both are acceptable — the key is no crash
-            if exitButton.exists {
-                exitButton.tap()
-            }
-        }
-
-        // Navigate to Month view and check share button there too
-        tabBar.tapMonth()
-        _ = app.waitForExistence(timeout: 3)
-
-        captureScreenshot(name: "share_no_data_month")
-
-        let monthShareButton = app.element(UITestID.Month.shareButton)
-        let monthShareExists = monthShareButton.waitForExistence(timeout: 3)
-
-        // With empty data, month share button should be absent
-        // or if present, should handle gracefully (no crash)
-        if monthShareExists {
-            monthShareButton.tapWhenReady()
-            _ = app.waitForExistence(timeout: 2)
-            captureScreenshot(name: "share_no_data_month_picker")
-
-            let exitButton = app.buttons["Exit"].firstMatch
-            if exitButton.waitForExistence(timeout: 3) {
-                exitButton.tap()
-            }
-        }
-
-        // Final verification: app is still responsive
-        tabBar.tapDay()
-        let emptyState = app.element(UITestID.Day.emptyStateNoData)
-        let moodHeader = app.element(UITestID.Day.moodHeader)
-        XCTAssertTrue(
-            emptyState.waitForExistence(timeout: 5) || moodHeader.waitForExistence(timeout: 2),
-            "App should remain functional after share-with-no-data flow"
-        )
+    }
+}
+
+final class ShareNoDataMonthTests: BaseUITestCase {
+    override var seedFixture: String? { "empty" }
+    override var bypassSubscription: Bool { true }
+
+    /// TC-119b: With no mood data, Month view share button is absent.
+    func testShare_NoData_MonthShareAbsent() {
+        let tabBar = TabBarScreen(app: app)
+        tabBar.tapMonth()
+
+        let monthShareButton = app.element(UITestID.Month.shareButton)
+        let shareExists = monthShareButton.waitForExistence(timeout: defaultTimeout)
+
+        XCTAssertFalse(shareExists, "Month share button should be absent when there is no mood data")
+
+        captureScreenshot(name: "share_no_data_month")
     }
 }