Add multi-image support for task completions and documents

- Add TaskCompletionImage and DocumentImage models with one-to-many relationships
- Update admin panel to display images for completions and documents
- Add image arrays to API request/response DTOs
- Update repositories with Preload("Images") for eager loading
- Fix seed SQL execution to use raw SQL instead of prepared statements
- Fix table names in seed file (admin_users, push_notifications_*)
- Add comprehensive seed test data with 34 completion images and 24 document images
- Add subscription limitations admin feature with toggle
- Update admin sidebar with limitations link

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

internal/handlers/subscription_handler.go

@@ -64,6 +64,17 @@ func (h *SubscriptionHandler) GetUpgradeTrigger(c *gin.Context) {
 	c.JSON(http.StatusOK, trigger)
 }
 
+// GetAllUpgradeTriggers handles GET /api/subscription/upgrade-triggers/
+func (h *SubscriptionHandler) GetAllUpgradeTriggers(c *gin.Context) {
+	triggers, err := h.subscriptionService.GetAllUpgradeTriggers()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, triggers)
+}
+
 // GetFeatureBenefits handles GET /api/subscription/features/
 func (h *SubscriptionHandler) GetFeatureBenefits(c *gin.Context) {
 	benefits, err := h.subscriptionService.GetFeatureBenefits()