Fix game mode task cycling: Only end game on complete-all mode

Critical fix for timed and score target game modes:

Issue:
- Game was ending when all tasks were shown regardless of game mode
- Timed and score target modes should continue cycling through tasks
- Only 'complete-all' mode should end when all tasks are finished

Fix:
- Updated loadMainTask() to check gameMode before ending game
- Complete-all mode: Ends game when all tasks completed (original behavior)
- Timed/Score modes: Reset usedMainTasks array and continue cycling
- Added console logging for task cycling in non-complete-all modes

Now game modes work correctly:
 Complete All: Ends when all tasks finished
 Timed Challenge: Cycles through tasks until time runs out
 Score Target: Cycles through tasks until target score reached

This enables proper infinite task cycling for time-based and score-based challenges!

game.js

@@ -2383,9 +2383,19 @@ ${usagePercent > 85 ? '⚠️ Storage getting full - consider deleting some imag
         );
         
         if (availableTasks.length === 0) {
-            // All main tasks completed - end game
-            this.endGame();
-            return;
+            // All main tasks completed
+            if (this.gameState.gameMode === 'complete-all') {
+                // Only end game in complete-all mode
+                this.endGame('complete-all');
+                return;
+            } else {
+                // In timed and score-target modes, reset used tasks and continue
+                console.log(`All tasks completed in ${this.gameState.gameMode} mode, cycling through tasks again`);
+                this.gameState.usedMainTasks = [];
+                // Recursively call loadMainTask to select from reset pool
+                this.loadMainTask();
+                return;
+            }
         }
         
         // Select random task and random image from task pool