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/EntryDeleteTests.swift

@@ -10,42 +10,27 @@ import XCTest
 final class EntryDeleteTests: BaseUITestCase {
     override var seedFixture: String? { "single_mood" }
 
-    /// TC-025: Delete a mood entry from the detail sheet.
+    /// TC-025: Delete the only mood entry -- mood header or empty state reappears.
     func testDeleteEntry_FromDetail() {
-        // Wait for entry to appear
         let firstEntry = app.firstEntryRow
-
-        guard firstEntry.waitForExistence(timeout: 8) else {
-            XCTFail("No entry row found from seeded data")
-            return
-        }
-
+        firstEntry.waitForExistenceOrFail(timeout: navigationTimeout, message: "No entry row found from seeded data")
         firstEntry.tap()
 
         let detailScreen = EntryDetailScreen(app: app)
         detailScreen.assertVisible()
-
-        captureScreenshot(name: "entry_detail_before_delete")
-
-        // Delete the entry
         detailScreen.deleteEntry()
-
-        // Detail should dismiss after delete
         detailScreen.assertDismissed()
 
-        // The entry should no longer be visible (or empty state should show)
-        // Give UI time to update
+        // After deleting the only entry, mood header or empty state should appear
         let moodHeader = app.element(UITestID.Day.moodHeader)
         let noDataText = app.element(UITestID.Day.emptyStateNoData)
 
-        let headerReappeared = moodHeader.waitForExistence(timeout: 5)
-        let noDataAppeared = noDataText.waitForExistence(timeout: 2)
-
-        XCTAssertTrue(
-            headerReappeared || noDataAppeared,
-            "After deleting the only entry, mood header or empty state should appear"
-        )
-
-        captureScreenshot(name: "entry_deleted")
+        let headerReappeared = moodHeader.waitForExistence(timeout: navigationTimeout)
+        if !headerReappeared {
+            noDataText.waitForExistenceOrFail(
+                timeout: defaultTimeout,
+                message: "After deleting the only entry, mood header or empty state should appear"
+            )
+        }
     }
 }