feat: Complete hybrid image upload system with URL compatibility

- Add hybrid image system supporting both file uploads and URL images
- Implement Active Storage for file uploads while preserving existing URL functionality
- Update Event model with both has_one_attached :image and image_url virtual attribute
- Create tabbed interface in event forms for upload/URL selection
- Add JavaScript preview functionality for both upload and URL inputs
- Fix promotion code validation issue in tests using distinct() to prevent duplicates
- Update all views to use hybrid display methods prioritizing uploads over URLs
- Update seeds file to use image_url attribute for compatibility
- Ensure backward compatibility with existing events using URL images

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

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

app/models/event.rb

@@ -24,7 +24,10 @@ class Event < ApplicationRecord
   has_many :promotion_codes
   has_one_attached :image
 
-  
+  # === Virtual attribute for backward compatibility with image URLs ===
+  attr_accessor :image_url
+
+
   # === Callbacks ===
   before_validation :geocode_address, if: :should_geocode_address?
 
@@ -34,8 +37,11 @@ class Event < ApplicationRecord
   validates :slug, presence: true, length: { minimum: 3, maximum: 100 }
   validates :description, presence: true, length: { minimum: 10, maximum: 2000 }
   validates :state, presence: true, inclusion: { in: states.keys }
+
+  # Image validation - handles both attachments and URLs
   validate :image_format, if: -> { image.attached? }
   validate :image_size, if: -> { image.attached? }
+  validate :image_url_format, if: -> { image_url.present? && !image.attached? }
 
   # Venue information
   validates :venue_name, presence: true, length: { maximum: 100 }
@@ -61,17 +67,36 @@ class Event < ApplicationRecord
 
   # === Instance Methods ===
 
-  # Get image variants for different display sizes
+  # Get image for display - handles both uploaded files and URLs
   def event_image_variant(size = :medium)
-    case size
-    when :large
-      image.variant(resize_to_limit: [1200, 630])
-    when :medium
-      image.variant(resize_to_limit: [800, 450])
-    when :small
-      image.variant(resize_to_limit: [400, 225])
+    if image.attached?
+      case size
+      when :large
+        image.variant(resize_to_limit: [1200, 630])
+      when :medium
+        image.variant(resize_to_limit: [800, 450])
+      when :small
+        image.variant(resize_to_limit: [400, 225])
+      else
+        image
+      end
     else
+      # Fallback to URL-based image
+      image_url.presence
+    end
+  end
+
+  # Check if event has any image (uploaded or URL)
+  def has_image?
+    image.attached? || image_url.present?
+  end
+
+  # Get display image source (uploaded or URL)
+  def display_image
+    if image.attached?
       image
+    else
+      image_url
     end
   end
 
@@ -167,6 +192,15 @@ class Event < ApplicationRecord
     end
   end
 
+  # Validate image URL format
+  def image_url_format
+    return unless image_url.present?
+
+    unless image_url.match?(/\Ahttps?:\/\/.+\.(jpg|jpeg|png|gif|webp)(\?.*)?\z/i)
+      errors.add(:image_url, "doit être une URL valide vers une image (JPG, PNG, GIF, WebP)")
+    end
+  end
+
   private
 
   # Determine if we should perform server-side geocoding