feat: API to list all attachments for a conversation (#7059)

Fixes: https://linear.app/chatwoot/issue/CW-1678/api-to-list-all-attachments-for-a-conversation

app/controllers/api/v1/accounts/conversations_controller.rb

@@ -22,6 +22,10 @@ class Api::V1::Accounts::ConversationsController < Api::V1::Accounts::BaseContro
     @conversations_count = result[:count]
   end
 
+  def attachments
+    @attachments = @conversation.attachments
+  end
+
   def create
     ActiveRecord::Base.transaction do
       @conversation = ConversationBuilder.new(params: params, contact_inbox: @contact_inbox).perform

app/models/conversation.rb

@@ -95,6 +95,7 @@ class Conversation < ApplicationRecord
   has_one :csat_survey_response, dependent: :destroy_async
   has_many :conversation_participants, dependent: :destroy_async
   has_many :notifications, as: :primary_actor, dependent: :destroy_async
+  has_many :attachments, through: :messages
 
   before_save :ensure_snooze_until_reset
   before_create :mark_conversation_pending_if_bot

app/views/api/v1/accounts/conversations/attachments.json.jbuilder

@@ -0,0 +1 @@
+json.payload @attachments.map(&:push_event_data)