refactor page/list movement

Signed-off-by: Hadi <112569860+anotherhadi@users.noreply.github.com>

internal/util/cursor.go

@@ -0,0 +1,30 @@
+package util
+
+// CursorMovePage moves cursor forward or backward by one page (perPage items),
+// clamped to [0, total-1].
+func CursorMovePage(cursor, total, perPage int, forward bool) int {
+	step := perPage
+	if step < 1 {
+		step = 1
+	}
+	if forward {
+		cursor += step
+	} else {
+		cursor -= step
+	}
+	if cursor < 0 || total <= 0 {
+		return 0
+	}
+	if cursor >= total {
+		return total - 1
+	}
+	return cursor
+}
+
+// CursorGotoBottom returns the last valid cursor index for a list of total items.
+func CursorGotoBottom(total int) int {
+	if total <= 0 {
+		return 0
+	}
+	return total - 1
+}