fix: scroll direction check always failed — read prevMinY before write

Bug: lastKnownMinY[entryId] was set to newMinY on line 83, then
read back on line 97 to check direction. Since it was just set to
newMinY, the check (lastKnownMinY[entryId] <= newMinY) was always
true, making isMovingUp always true, so the guard always failed.

Fix: Read prevMinY BEFORE writing newMinY. Compute isScrollingDown
from the delta between prev and new. Use that boolean in the guard.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ios/Platform/Platform/Features/Reader/Views/EntryListView.swift

@@ -69,17 +69,21 @@ struct EntryListView: View {
                             guard entryHeight > 0 else { return }
 
                             // --- Scroll direction + activation ---
-                            if let prev = lastKnownMinY[entryId] {
+                            let prevMinY = lastKnownMinY[entryId]
+                            let isScrollingDown: Bool
+                            if let prev = prevMinY {
                                 let delta = prev - newMinY // positive = scrolling down
-                                if delta > 2 {
+                                isScrollingDown = delta > 2
+                                if isScrollingDown {
                                     cumulativeDown += delta
                                     if cumulativeDown > activationThreshold {
                                         trackingActive = true
                                     }
                                 }
-                                // Don't reset trackingActive on upward scroll —
-                                // just don't mark anything. Keeps cumulative progress.
+                            } else {
+                                isScrollingDown = false
                             }
+                            // Store AFTER reading previous value
                             lastKnownMinY[entryId] = newMinY
 
                             // --- Visibility tracking ---
@@ -92,11 +96,8 @@ struct EntryListView: View {
                             }
 
                             // --- Mark-as-read ---
-                            // Current scroll direction for THIS entry is "down"
-                            // if its minY decreased since last check
-                            let isMovingUp = (lastKnownMinY[entryId] ?? 0) <= newMinY
                             guard trackingActive,
-                                  !isMovingUp,
+                                  isScrollingDown,
                                   !entry.isRead,
                                   !markedByScroll.contains(entryId),
                                   wasVisible.contains(entryId),