docs(ios): add testing instructions for rollover interval

Add inline comments and documentation explaining how to temporarily
change rollover notification intervals from 24 hours to 2 minutes
for testing purposes. Comments specify exact line numbers and values
to change, making it easy to switch between production and testing
modes without losing context.

Changes:
- Add TESTING section to calculateNextScheduledTime() documentation
- Add inline TESTING comments at three change points:
  * Calendar date addition (24 hours → 2 minutes)
  * Fallback time calculation (24 hours → 2 minutes)
  * Duplicate prevention threshold (1 hour → 1 minute)

All code remains at production settings (24-hour intervals).

ios/Plugin/DailyNotificationScheduler.swift

@@ -389,6 +389,10 @@ class DailyNotificationScheduler {
      * 
      * @param currentScheduledTime Current scheduled time in milliseconds
      * @return Next scheduled time in milliseconds (24 hours later)
+     * 
+     * TESTING: To test with shorter intervals (e.g., 2 minutes), change:
+     * - Line ~404: `.hour, value: 24` → `.minute, value: 2`
+     * - Line ~407: `(24 * 60 * 60 * 1000)` → `(2 * 60 * 1000)`
      */
     func calculateNextScheduledTime(_ currentScheduledTime: Int64) -> Int64 {
         let calendar = Calendar.current
@@ -396,8 +400,10 @@ class DailyNotificationScheduler {
         let currentTimeStr = formatTime(currentScheduledTime)
         
         // Add 24 hours (handles DST transitions automatically)
+        // TESTING: Change `.hour, value: 24` to `.minute, value: 2` for 2-minute testing
         guard let nextDate = calendar.date(byAdding: .hour, value: 24, to: currentDate) else {
             // Fallback to simple 24-hour addition if calendar calculation fails
+            // TESTING: Change `(24 * 60 * 60 * 1000)` to `(2 * 60 * 1000)` for 2-minute testing
             let fallbackTime = currentScheduledTime + (24 * 60 * 60 * 1000)
             let fallbackTimeStr = formatTime(fallbackTime)
             NSLog("DNP-ROLLOVER: DST_CALC_FAILED current=\(currentTimeStr) using_fallback=\(fallbackTimeStr)")
@@ -456,6 +462,7 @@ class DailyNotificationScheduler {
             let lastRolloverTime = await storage.getLastRolloverTime(for: content.id)
             
             // If rollover was processed recently (< 1 hour ago), skip
+            // TESTING: Change `(60 * 60 * 1000)` to `(60 * 1000)` for 1-minute threshold when testing with 2-minute intervals
             if let lastTime = lastRolloverTime,
                (currentTime - lastTime) < (60 * 60 * 1000) {
                 let lastTimeStr = formatTime(lastTime)